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IB Computer Science Internal Assessment Dossier Guidance

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1. Dave Mulkey Germany June 2008 16 32 Variables Data Structures and Methods Remember this is not a complete dossier Your dossier will be much longer The example only shows two of the stories from the analysis but you should do all your stories and goals Now we can extract ideas for variables data structures and methods e Nouns Variables student name teacher name class name excuse date excuse absence String containing fields e Lists arrays and files names file teachers file absent students array list of absences file students file book of absences file parents file e Verbs tasks and methods take attendance mark down arrives late change attendance decide excused or unexcused write excuse Classes from Prototype The user stories are usually about the existing system The solution will include new ideas that make things easier and more efficient The prototype was a first attempt at designing the solution So we can extract more useful ideas from the prototype especially methods and classes An interface screen is usually a class as well as complex data items e More Methods select class mark absent student delete absence late save absences view student enter excuse see today s data e GUI Interface Classes Take Attendance Interface Clerk s Interface Daily Summary Excuse Entry Screen e Data Record Classes Absence Record Name Class Teacher Date Excuse
2. For full marks The student discusses the effectiveness and efficiency of the solution and suggests alternative processes and improvements The student suggests alternative approaches to the solution and the design process Guide p 62 Examples Here are some on line examples which show how to write stage D Complete Dossier http ibcomp fis edu Projects StudentSample2007 pdf Teacher Support Material http occ ibo org ibis documents dp gr5 computer_science d_5_comsc_ts m 0809 1 e pdf IB Computer Science Stage D Step by Step 2 to 3 weeks 10 15 hr User Documentation Before doing the final testing and evaluation writing user documentation helps the programmer organize their thoughts about the program It may also be useful to write some user docs before finishing the program FINAL Test Output All the testing and printing in this section must be done after the final program has been written This is not a debugging session but a documentation session There will probably be errors in the program these must be documented rather than being fixed If major problems surface it may be necessary to go back and re finish the final version But after that all the testing must be performed again Complete Sample Run If possible produce a single session showing typical use of all the required features and capture and annotate output for this entire session This will include only single examples of normal data n
3. IB Computer Science Program Structure Variables data structures and methods are only pieces of a program A working program also needs a sensible structure The general term for structural elements is modules Classes arrays and files are all modules in this sense Inside a single class methods break up the class into pieces which we can also think of as modules OOP Object Oriented Programming depends on objects as the major structural concept A file is represented by an object a BufferedReader or RandomAccessFile An array is also an object created with the new command Complex data collections like the data for a single absence can be stored in an object containing a variable for each field Although all the modules in your program might be classes you still need to distinguish between the functions of these various objects There is no right way to structure a Java program but here is one possibility e Teacher Interface Class GUI Components Classes List Students List Absent List Save Button Data Structures absencesArray absencesFile Methods chooseClass showStudents chooseStudent addAbsence deleteAbsence saveAbsences e Clerk s Interface Class GUI Components StudentName AllDataButton EnterExcusesButton Data Structures allStudentNames Array Methods chooseName showAllData showExcusesInterface This would be a much longer list for a real dossier Inte
4. Internal Assessment Dossier Dave Mulkey Germany June 2008 26 32 Slow and Careful The prototype is probably a quick and dirty job just to get started Now the Alpha version requires slow work and careful attention to detail As the program grows larger debugging is increasingly difficult A few tips e Comments help a lot You will work on this program for several weeks You will get confused You will forget some of the things you did in the beginning If you write comments as you go it s much easier later when you look at the code and try to understand what you wrote e Meaningful names make the program easier to read we call it self documenting A variable named X might be used to count through an array In a two dimensional array you can use X and Y But if you use ROW and COLUMN it s much easier to keep track of what is going on see style guide on next page e Indentation makes it much easier to see where loops if blocks and methods begin and end All three of these are expected for C1 so you will be rewarded with marks But the big reward is finishing the program in less time Getting Unstuck Student programmers get stuck sometimes They change something in their program it doesn t run correctly and they cannot find the problem DON T stay up all night banging on the keyboard hoping to get lucky Even worse DON T erase big sections of code and start over You are permitted to get help fr
5. Dave Mulkey Germany June 2008 13 32 Mastery is the problem hard enough Candidates must ensure that the problem provides scope for fulfilling the Mastery Factor requirements If you are unsure ASK THE TEACHER A data base oriented problem generally provides the most straightforward way to meet the IA requirements and criteria Data files are immediately included and there is an obvious need for sorting and searching However other problems are possible and the use of data files need not be central to the program If a non database problem is chosen teachers should help the students find sensible appropriate uses for files A few ideas e Results file A simulation or math program can store results in a data file for later analysis This is especially sensible if the program creates lots of results such as a simulation producing output every minute for 24 hours or a graphing program generating hundreds of coordinates e Keyword Validation Many input operations require a word to be typed which is in a list of valid entries for example names of months names of geometric figures etc These could be stored in a data file along with associated information The validation routine might permit adding new keywords like a spell check that permits changing the dictionary e Conversion Translation A program could be internationalized by allowing constants and instructions to appear in a variety of languages Ot
6. Guide p 54 is realistic Before Starting The dossier requires students to think ahead during analysis and design Thinking ahead is difficult and requires guidance and instruction Students must know enough Java to know what is possible especially as they must design data structures and algorithms during Stage B as well as knowing about some reliable systematic methods to use during Stage A Many teachers try to start the dossier early in the second year of the course Before that point the students don t really know enough Starting later is possible However many students fail to finish on time because they start too late or because a poor design caused them to waste a lot of time throwing away work and starting over too often Preferably students will complete these stages in the order given Guide p 53 However students commonly encounter unexpected difficulties t While programming and must revise the original design before continuing IB Computer Science A Analyzing Stage A starts with choosing a problem and finding an intended user Many students want to start by writing a program but that is not the intention of the dossier assignment Starting with programming usually leads to a poor design missed deadlines and general difficulties Stage A Analysis select a problem AND an intended end user analyze the problem using a systematic method create a prototype and discuss it with the user
7. Bobby Math 10a ESL 2b Science 10c Clown Math 7x English 7x Science 7x Eddie Math 10a English 10a Science 10a Adams Baker Bozo Eagle This file will be accessed by various parts of the system including e Teacher Attendance populate a class list e g Math 10a e Clerk Interface populate the Student Name box Dave Mulkey Germany June 2008 18 32 Daily Absences File For each class each day the absences will be saved into a simple text file formatted as shown below The files will automatically be save in a central folder on a LAN server giving the office access to all the files Daily Absences EinsteinA 01apr2008 File Alice Math 10a Einstein A 01 Apr 2008 Eddie Math 10a Einstein A 01 Apr 2008 Adams Eagle The clerk s module will open all the teachers files and copy the absences into the AllAbsences file where excuses will be added later All Absences File AllAbsences is a RandomAccessFile containing an absence record for each student that misses a class If a student is out sick for an entire day there will be 6 absence records for that students on that day Notice that on the day of an absence the record will contain as an excuse This will get changed later normally the next day AllAbsences File Eagle Eddie ath 10a Einstein A 01 Sep 2008 Sick Exc Bozo Clown Engli
8. but should connect the goals to user stories Although not specifically required most dossiers will attempt to make an improvement over the previous system These improvements can arise from a wish story e g the user says I wish that it worked like this and then describes something they want like the Skipping Students story Programmers should not invent cool features without discussing them with the user to see whether they are actually needed All the goals should be connected to user stories Remember keep it simple IB Computer Science Keep It Simple Creeping featurism refers to the temptation to add more and more features to make the program better and better Unfortunately this usually leads to unfinished programs that do absolutely nothing that s NOT better In the end all the features in the program must actually WORK Initial Design At some point the student needs to start thinking about a possible structure for the solution an initial system design The student should examine the user stories and preliminary goals and think about e What tasks must be performed What are some automated processes that will support the user in these tasks e What data is required for the tasks and how should it be input e What results must be produced How should they be displayed e What data files are needed for storing data permanently The initial design can be displayed as a diagram v
9. that cannot be satisfied If there are also no arrays or files there will also be no searching or sorting and then it becomes impossible to achieve 100 mastery Are there enough mastery factors Since teacher judgment is involved and not all teachers are the same it s possible that a teacher awards 10 mastery factors but a moderator only awards 8 or 9 The penalty for 2 missing mastery factors is 20 which almost certainly lowers the final grade by or more so this disagreement could be quite costly The simplest way to avoid this danger is to plan on satisfying MORE than 10 mastery factors In any case all the mastery factors are techniques that make programs more flexible and more successful So using more mastery factors probably has other benefits Internal Assessment Dossier Dave Mulkey Germany June 2008 25 32 Are the mastery techniques trivial or not Keep in mind that mastery factors are only satisfied if they are used for a non trivial purpose That means the program actually benefits from the use of that technique For example an array containing one single item is unlikely to be beneficial If the program writes a data file but never reads it again then how is the program benefiting Common examples of trivial use are e a method returns a value but the value is never used for anything e an ADT has it s data changed directly without using internal methods e loops are used inefficiently or incorr
10. Rush Steve McConnell 1999 Microsoft Press
11. copied into the list of absent students If a student arrives late the teacher clicks on the name in the absent list and the name disappears When finished click Save Clerk s Interface Mercury Freddie See All Data for Today Enter Excuses The Student Name box can be a drop down list of all student names Eagle Eddie Math 10a Einstein A 01 Apr 2009 Adams Alice History 10a Churchill W 01 Apr 2009 Exact details of this data structure are not necessary this is just a basic concept so we can discuss what data needs to be stored not how Daily Attendance Summary 01 Apr 2009 Change Date Adams Alice Math 10a Einstein A Eagle Eddie Math 10a Einstein A Adams Alice History 10a Churchill W Print Enter Excuses Mercury Freddie Math 10a Einstein A 1 Sep 2008 Sick Excused Math 10a Einstein A 2 Sep 2008 Skipped Unexc History 10a Churchill W 5 Se 2006 mee Click on any absence to enter change the excuse Type An Excuse For Mercury Freddie History 10a Churchill W 5 Sep 2008 2 _Sick Excused IB Computer Science Happy User Automation User friendly has been misunderstood as cheerful pretty software that makes users happy The actual key to user satisfaction is reliable and usable software This is software that does what
12. for the previous day print out part of the AllAbsences file showing the changes display one student s absences showing excuses For full marks The student includes evidence that the program functions well The student successfully achieved all of the objectives from A2 The teacher should run the program with the student to confirm that the program functions and that it produces the hard copy output submitted with the program dossier Guide p 61 This section does not need its own hard copy output but it might make reference to specific pages in D1 If the goals include some sort of error checking or usability goals then The finished program should function well That means specific sample output must show that these goals were achieved This E compiles without enor may require thorough testing of the program with correspondingly extensive sample output all features execute correctly at least most of the time 2 z g ims y Documentation of the success of the program must include a list of all the e the user can successfully use the program as intended goals criteria for success together with sample output demonstrate that e there are few or no run time errors the program actually achieved these goals The easiest way to connect the goals to the sample output is with a table Many students fail to reach the functions well level due to that lists each goal together with a reference number page
13. looks good like 4 straightforward steps However each loop might iterate several times until it s finished That means the programmer might return again and again to the design stage make changes and then continue on the program There will probably be deficiencies in the original detailed design It s common to discover after finishing the design some useful low level methods that make your program simpler For example e validatedExcuseInput returns String This repeatedly asks for an excuse to be typed in If the typed excuse is not in the official list Exc Unx Tdy then the method asks again At the end it returns a valid excuse OR e chooseExcuse returns String Displays a dialog with a drop down list containing valid excuses The user chooses an excuse and this is returned Either one of these would do the job Students seldom think in such detail that they design methods before programming for individual inputs It s acceptable to change the design in parallel with the programming changes But it isn t actually necessary to have ALL the small insignificant methods in the design document Note that it is not permitted to write the program and then copy Java code into the design document So if a student wants to add something to the design say a special sorting algorithm they should write a description with pseudocode in the design then use the ideas to write the Java code
14. number to e starting too late or working too slowly sample output in section D1 It is not necessary to duplicate all the output e attempting overly ambitious features for sections C3 and D1 but there must be a clear connection e sloppy testing Remember an IB moderator will never see the program running So they can only judge the work by what is shown on paper and this must be The Program MUST RUN Keep It Simple complete and well organized Often the program can be considerably more difficult than anticipated making it difficult to meet the final deadline Too many students submit dossiers with little or no hard copy output as a result Rather than submitting a non functional program it is better to submit a simpler program that runs even if it does not meet all the objectives from A2 If it doesn t run the student is penalized twice in C4 and in D1 There may also be a penalty in the mastery factors because code that was supposed to demonstrate mastery actually does not work IB Computer Science Stage C 5 6 weeks 20 30 hr Incremental Development Cycles Code Test Fix Step by Step Development should be cyclic The Beta version is an expansion or elaboration of the alpha version Each cycle includes programming testing and debugging Comments in the source code should document the development Functional Prototype This is just getting started Make something that has a couple functioning features just so
15. program Students must solve a real problem for a specific end user by analyzing the problem designing a solution writing a program in Java and documenting the program and resulting system At the end students print out the program listing and all the documentation and submit it on paper It is assessed by the teacher and then checked by IB examiners The Dossier The diagram outlines the Software Life Cycle emphasizing the importance of meeting goals and de emphasizing programming Writing the program is necessary but not sufficient Real software gets redesigned and reconstructed software life cycle bu the IB dossier only requires going around the big loop one time Internal Assessment Dossier Dave Mulkey Germany June 2008 2 32 Four Stages The dossier has four stages e Stage A Analysis e Stage B Detailed Design e Stage C The Program e Stage D Documentation The four stages are normally completed over a fairly long period of time several months This extended time line is not a requirement but most students find it impossible to do it all in a single month The IBO Guide recommends 25 SL or 35 HL hours of teacher contact time plus further computer access time Guide p 48 so probably more than 50 hours in total The actual time commitment is difficult to measure as dossier work usually overlaps with instruction about Java techniques And the suggestion of 60 100 printed pages
16. students for the class from the Students file The teacher marks absent students and then saves the data into a text file loadClassT ist for that class one file for each class on each day markAbsent a markLate Clerk s Interface save ____ gt T The attendance clerk works in the office She will use the the Clerk s Daily Absence Files Interface for the following tasks Teacherl Class1 Students File name class1 class2 e Collect Absences opens all the files for individual classes and copies Clerk s Interface Teacher1 Class2 the data into the AllAbsences file collectAbsences lt _ lt cote SES Enter Excuses as students bring in excuse notes the clerk decides E lt 4 Teacher2 Class1 i i l loadStudentNames caber CESS whether an absence was excused or not and enters corresponding text into enterExcuses the record in the AllAbsences file printDailySummary e Print Daily Summary prints a daily summary of all the absences for one day The clerk will give a printed copy to the vice principal AllAbsences RandomAccess File of Absence Records This is really the central module for attendance management The Teacher Interface is basically just an input module Daily Summary Data Extraction appears on screen This module must copy names and classes out of the school s scheduling then can be printed bsence Record database and store it
17. to the student s name either X for excused or U for unexcused At the end of each week the clerk reviews the entire list and writes a list of students who have been absent too often this is a different number each week The list goes to the vice principal who either talks to the student calls the parents or both Input list of student names with absences X and U Process find students with too many absences Output list of students with too many absences Catching Skipping Students User Story This does not work very well with the paper system The office only gets the lists from teachers at the end of the day So if a student skips periods 3 and 4 it s only noticed at the end of the day It is also difficult for the clerk as she must check multiple lists to find out whether a student was absent from one class but not from others She deals with this by making check marks on a scrap copy of all the student names but it is time consuming and unreliable She wishes this were easier e g automatic Input absence lists from all teachers Output checkmarks on scrap paper Processing search for students with only 1 or 2 marks Storage scrap paper copies are stored in a notebook but rarely used This set of stories is incomplete It does not indicate how the clerk knows which students from yesterday need excuse notes This might indicate an actual hole in the system or it might just be incomple
18. you can get started and show the user something This could be done in Stage A instead of the interface prototype but the interface prototype is probably easier and more useful Don t invest too much time in this you might end up throwing it away Alpha Version Start with a simple version with a simple interface and meeting only a few goals this might be a small extension of the prototype Develop and debug this version Add more functionality Debug some more Accomplish all the difficult technical tasks e g build the base of library functions necessary to make the rest of the program work This is a technical release not a user release But DON T leave bugs in this version for later The bugs are easier to find in this smaller version than hunting them down later in a big program Make sure ALL the mastery aspects are accomplished in this version The programmer should assess this version themselves Supervisor Check Have the teacher check that all the mastery factors have been done adequately If not you will need to fix this in the next version Internal Assessment Dossier Dave Mulkey Germany June 2008 29 32 Beta Version Add any missing or incorrect functionality Add or fix any missing mastery factors Finish the user interface and usability features Add as much error handling as you can think of Make sure the program meets all the criteria for success User Beta Testing Get the user to spend some tim
19. you could have written a functional prototype rather than an interface prototype A functional prototype is a very simple limited version of the program that only implements a few of the features This is tempting for students who want to start programming but as one software engineer said Plan on throwing your functional prototype away you will so you might as well plan on it This is distressing so it might be better to wait until Stage C to make a prototype So what is a functional prototype It should display a very simple interface requiring only a few inputs and then perform only very basic automated functions There are no nice features like drag and drop and pretty colors There is probably little or no error handling Stage C requires documentation of User Friendly features and Error Handling so you will need to add these eventually but you don t need to have them in the very first version Below is a functional prototype for the Teacher Interface module import java awt import java io import java util Date public class Teacher extends EasyApp public static void main String args new Teacher Label lbla addLabel Classes 50 50 100 20 this List classes addList Math 9a Math 10a Math 10b Come Sci 1 Come Sei 2 50 70 100 200 this Label lblu addLabel Students 200 50 100 20 this List students addList 200 70 100 200 this Label lbls addLab
20. A That means the program must actually function and it should be possible for the intended user to use the program successfully Stage C The Program write a program following the design satisfy the Criteria for Success goals from Stage A make it usable including user friendly features make it robust reliable by handling errors fulfill the Mastery Factor requirement at least 10 items The program must demonstrate mastery of Java programming techniques required for the course That sounds like a text book exercise but it s more than that Students must write methods and classes that function correctly when the entire program runs not only under simplified test conditions Students should avoid simplistic solutions They should use more powerful and flexible techniques whenever possible as that leads more easily to a successful program and satisfies mastery factors D Documenting Stage D Documentation hard copy printed output of running and testing the program evaluation describing what worked well and what didn t user documentation a user s manual Hard copy output consists of screen captures of the running program An IB moderator will never see the program running they will only see this printed output so it must be complete and extensive User documentation will contain similar screen shots with explanations of how to use the program The evaluation includes suggestions for improv
21. IB Computer Science IB Computer Science p2 Internal Assessment Dossier Guidance w Dave Mulkey Usingen Germany June 2009 p5 Preface The dossier is the Internal Assessment assignment for IB Computer Science The course covers Java programming in considerable detail more for Higher Level than Standard Level The dossier is the primary assessment tool for the programming part of the course It counts 35 of the final IB grade with two exams counting 32 5 each p15 The dossier requires the students to use reliable software design techniques in addition to using correct Java programming techniques Since students have unlimited time to devote it should be possible to score a high mark on this project Unfortunately dossier marks don t tend to be any higher than written exams This seems to result from some misunderstandings of the requirements of the dossier Many students fail to address required elements and lose marks for rather silly reasons p23 The intention of this document is to help IB students understand the dossier requirements and avoid mistakes as well as providing suggestions to make the project easier and make the students more successful with less frustration and effort The recommendations and suggestions are the result of many years of IB teaching experience plus years of work as an IB moderator for the dossier but these notes are not official in any sense For official answer
22. Make a list of the mastery factors you will demonstrate with the names of data structures and methods which will demonstrate them Supervisor Approval Obtain supervisor approval before proceeding to programming The supervisor should ensure there is sufficient scope to achieve 10 or more mastery aspects He she should also ensure that classes data structures and algorithms adequately support the goals stated in the criteria for success The plan must be achievable within the prescribed time frame IB Computer Science Stage C The Program If students have learned Java programming for a year or more before starting the dossier then writing the program should be relatively straightforward though it probably takes more time than expected A good design should make it easier and quicker Iterative Development The following diagram demonstrates an iterative model for software development It starts with a prototype and proceeds through several iterations loops including alpha beta and release versions This is based on Extreme Programming which involves users directly in the development process After each loop version the programmer should let the user test it This is a suitable concept for the dossier where students should be working directly with the users Internal Assessment Dossier Dave Mulkey Germany June 2008 23 32 Functional Prototype Get Started During Stage A Analysis
23. adLine for int f 0 f lt files length f if info indexOf classID gt 0 file open files f name parseStudentName info loop through file add name to Names list box absence file readLine append absence to masterFile j parseStudentName info pre condition info contains a student record name class1 class2 post condition return the name field return String name createListOfFiles directory pre condition none post condition all file names in directory returned in an array return String fileNames Oooh this is a tricky one need to read the manual return info substring 0 info indexOf You cannot leave the tricky methods blank you must actually write something It can be vague in some cases but not missing i IB Computer Science There are lots more methods needed certainly all those named by extracting verbs from the user stories Very simple methods need not appear for example a method that asks the user which printer they wish to use But students must describe all methods that contain loops or complex logic or file access Most importantly any methods that demonstrate mastery factors should be described so teachers can see whether the student is going to demonstrate enough mastery factors Many students give up when writing the algorithms Why e They have trouble thinking ahead that far s
24. alse for int c 0 c lt absences getItemCount c if absences getItem c equals name found true if not yet absent add name to absences list if found false absences add name public void saveAbsences String fileName output fileName try PrintWriter file new PrintWriter new FileWriter fileName for int c 0 c lt absences getItemCount c file printin absences getItem c file close catch IOException ex output ex toString IB Computer Science Improvements Once the prototype is working it requires significant rework and expansion First it needs lots of comments to improve readability Keep in mind that an IB moderator will never see the running program so they will be required to read the program to decide whether it satisfies mastery factors HELP them read your program by using comments Mastery Factors Students and teachers should already think about mastery factors during Stage B to avoid producing a solution that is too simple The design must provide enough opportunities to satisfy at least 10 mastery factors If an HL student designs a solution with no files it cancels out 3 mastery factors If the design also omits ADTs it would be impossible to achieve 100 mastery Weak SL programmers might be tempted to write one long program in the main method with no other methods Then there are 3 mastery factors
25. am is for everyone That makes the problem very difficult to define and even more difficult to solve Choose one specific user for discussions you may wish to think about a group of similar users but this should be a small group All teachers is a bad choice but several teachers in the math department is okay All students is a bad choice but some of the IB Diploma candidates at my school is better Think about the intended user when choosing the problem Making a personal calendar is different for a businessman than for an elementary school student Let the user help you talk to them regularly If you are in the middle of writing the program and trying to decide how a specific interface should look a brief conversation with the user might reveal that they are happy with a very simple interface or that they actually don t need that feature at all thus saving time and energy for the programmer Take notes every time you are talking to the user Otherwise you must keep everything in your head More likely you will simply forget and ignore some of the useful ideas that came from user discussions Find a sophisticated user one who knows something about computers and uses them often Otherwise they will either have lots of impossible ideas e g I want to use a microphone to talk to the computer or even worse they might have no ideas at all e g I don t care anything s okay Internal Assessment Dossier
26. an outline this is easy to expand Teacher teacher s interface uses Students File Absence Record Daily Absence File does loadClassList markAbsent markLate save Clerk clerk s interface uses Daily Absence Files Students File Absence Record AllAbsences File does collectAbsences loadStudentNames enterExcuses printDailySummary Students File contains name class1 class2 class3 for all students Absence Record contains name classID teacher date excuse Daily Absence File for One Teacher contains name classID teacher date AllAbsences Master File contains all AbsenceRecords for entire year and all students For the finished dossier a diagram is better than an outline as it gives a quick and clear overview of the entire design This helps the student user and teacher and moderator understand the overall structure of the program IB Computer Science Internal Assessment Dossier Dave Mulkey Germany June 2008 21 32 B3 Modular Organization Diagram To receive full marks in B3 the student must have described all the modules and has shown the connections to data structures and methods Guide p 58 So a description such as the following is required Data Extraction extracts scheduling data from the school s scheduling database Teacher Interface The Teacher Interface is used by teachers to take attendance during each Teacher Interface class It loads the names of
27. ation The following examples are abbreviated to save space A real dossier must present ALL data structures and ALL non trivial algorithms and show modules with connections to ALL the data structures and algorithms IB Computer Science B1 Data Structures Data structures refer to arrays files records and Abstract Data Types This does not include simple primitive variables unless a String contains formatted data with several fields like Mon p1 Math So individual ints doubles and Strings need not be described here Remember that sample data IS required Using realistic sample data makes the descriptions easier to write Random data is less helpful Student Names There are several functions that require a list of student names Since names will be recorded in absence records misspelled names would cause problems So it s best to do all name inputs by selecting from a list All Students File The program will start with a file containing the names of all the students in the school The names will be written Last First one name per line in alphabetical order Each name will be followed by a list of ClassID fields for each class the student takes Hopefully these names and class Ids can be exported from the school s scheduling database and transformed into a simple sequential text file Internal Assessment Dossier AllStudents File Alice Math 10a English 10a Science 10a
28. e principal might need a list of the students with too many absences another user The user is an integral part of the development process their needs should guide the design of the software This is a simple example students should NOT actually choose this problem Internal Assessment Dossier Dave Mulkey Germany June 2008 5 32 Use the User s Stages Al and A3 require students to discuss the problem with the intended user Many students find this uncomfortable and don t know what to talk about Many users don t want to spend time on this either All too often the user and the student don t understand each other and don t exchange useful information As a student you probably are not an expert in the field of your chosen problem Although you attend school you probably never thought much about the school s attendance system The user has a lot more understanding of the problem than a student so students should take advantage of the user s expertise Otherwise the resulting program can be far too simplistic to satisfy the user s goals or can become unnecessarily complex and thus very difficult to complete If there are lots of users say 50 teachers you might want to distribute a questionnaire rather than having conversations with so many people But it is still useful to talk to a specific user Choose one who is particularly helpful Let them help you figure out what is important and what is not Let them explai
29. e testing the beta version and to make comments about needed improvements Most important are complaints about failure to meet success criteria User s may suggest usability and performance improvements note these for inclusion in the next version Finished Version The finished version of the program should correctly address all the following adequately meet all the criteria for success demonstrate 10 or more mastery aspects adequate usability adequate error handling adequate performance speed and or data storage efficiency Usability and Error Handling Documentation Write descriptions and explanations of usability considerations and error handling features Where appropriate refer to criteria for success Supervisor Check Check that suggested improvements above were made and that mastery aspects have been achieved IB Computer Science Stage D Documentation The main purpose of this section is to show the end user teacher and examiner what your program can do Don t start too late Make sure you finish your program in time to still do all the documentation D1 Annotated Hard Copy Since the IB moderator never sees the program running all the information about the program must be printed on paper This must include comprehensive documentation of all functionality of the program For full marks The student includes a complete set of annotated sample output testing all the objectives in crit
30. e too difficult perhaps not too difficult for the student s skills but too difficult in terms of time requirements Games sound exciting However they tend to be much more difficult than first appearances indicate And anything with animation is discouraged because it cannot be recorded on paper Remember IB moderators only see the paper they never see the running program IB Computer Science Some Suggestions Before you give in and take the easy route of a data base problem consider some other possibilities Realistic Problems Although not strictly required a real or realistic problem generally provides more opportunities for the students to do some investigation and pre coding design and makes the task of writing user instructions more sensible and easier Realistic problems make many parts of the documentation process easier Familiar Topics Candidates need to understand the problem that they are solving For this reason many candidates choose problems that exist in school or in areas with which they have considerable familiarity Some examples e Library circulation and customer data base e On line quiz tutorial for a school subject math science English etc e Student grades attendance schedules e School bus routes and rider data base e Travel vacations exchanging money dates and times problems airline reservations e Retail stores video lending inventory sales ordering e Entertainment TV
31. ectly e recursion is used where a loop would be more sensible e aclass extends another class but never uses the inherited members Alpha Version Functionality The purpose of the prototype was just to get something working The next iteration is an alpha version this is the time to get everything working Well not really everything but this should implement all the essential functionality especially all the mastery factor algorithms For example all the file operations should function sorting searching ADTs etc You might leave some usability improvements and some error handling out at this stage This stage would require considerable reworking of the prototype e When it loads a class list of names these must come from a file rather than having the names hard coded in the program e It s not necessary to have ALL the class list files finished but a representative sample should be present at least 3 teachers and 3 classes for each teacher and maybe 5 names in each e Absence data should be saved in the correct format not just as a list of names IB Computer Science ALL the modules must be programmed e g the clerk s interface too They must work to some extent but not necessarily perfectly You ll probably want to add some error handling whatever is easy to include but can leave the really detailed error handling for the next version Spiraling Back The development spiral
32. el Absent 350 50 100 20 this List absences addList 350 70 100 200 this Button save addButton Save 500 100 50 50 this String teacherName EinsteinA IB Computer Science public Teacher this setTitle Teacher Attendance Interface public void actions Object source String command if source classes loadClassList classes getSelectedItem else if source students markAbsence students getSelectedItem else if source absences absences remove absences getSelectedIndex else if source save String today new Date toString substring 0 10 2008 saveAbsences d attendance teacherName classes getSelectedItem N today xe 7 public void loadClassList String classID Stub version this needs to load from disk files students removeAll if classID equals Math 10a students add Young Al tudents add Younger Betty students add Yung Carl n Internal Assessment Dossier Dave Mulkey Germany June 2008 24 32 else if classID equals Comp Sci 1 students add Jung Fred students add Older Pops students add Younger Betty students add Zonker Zeke else output Class ID is unknown public void markAbsence String name check whether name is already absent boolean found f
33. ement IB Computer Science Internal Assessment Dossier Dave Mulkey Germany June 2008 4 32 Planning Before Doing Each stage requires a different view of the system For example when the user describes the problem they will talk about completely different issues The dossier requires students to work through a logical thorough reliable than a programmer who is trying to produce a solution design process before writing a Java program It requires students to start at the user s end analyze a problem to produce goals work through a The diagram below outlines different issues at various stages in the sensible design follow good software development principles and finish Software development process It may be overwhelming but it clearly with thorough testing and documentation Students must work in each of shows how developers change gears from one stage to the next these stages using appropriate tools and strategies at each stage Real World Analysis System Program Programming Problem Design Design Program Code Features Methods v Si Needs Daw Java amp Wishes Classes Language s Feelings Interia Compiler Q Algorith People Lori a Modules A Data Structures Applications i on Data Files Money Pe Schedules Resources Infrastructure r T
34. erion A2 The sample output needs to be organized and annotated so that it makes sense to someone reading it The following organization is suggested e Acomplete sample run showing all the features of the program executed as might happen in a single session or several consecutive sessions For the attendance application it could contain two teachers taking attendance for several classes print out the resulting data files the clerk collecting the absences print out part of the resulting AllAbsences file print the daily summary report clerk enters excuses for the previous day print out part of the AllAbsences file showing the changes display one student s absences showing excuses e Various testing of error handling features e Any particularly interesting usability features e Organized testing of ALL Criteria For Success from A2 This sounds like lots of pages and it is The guide says variable but it s probably 30 pages or more Many dossiers have too little sample output Internal Assessment Dossier Dave Mulkey Germany June 2008 30 32 D2 Evaluating Solutions The Guide recommends answering the following questions e Did it work e Did it address the criteria for success e Did it work for some data sets but not others e Does the program in its current form have any limitations e What additional features could the program have e Was the initial design appropriate Guide p 62
35. ery simple at first List of All Students Teacher Takes _ Class Lists Attendance Absences gt Clerk s Flow of File Interface Data 0 Flow of Enter Control Excuses Internal Assessment Dossier Dave Mulkey Germany June 2008 8 32 So what about the PROGRAM Starting with programming without careful planning and design is called code and fix programming The second reason code and fix development is appealing is that it requires no training The sparkle and luster of quick early progress is one reason that customers and managers continue to fall for code and fix development McConnell p 15 16 McConnell points out that careful planning is not wasted time it actually shortens total development time Computer Science students are anxious to get down to the business of writing a program In all honesty the users are probably also anxious to see something they d really like you to open up a box of software install it and voila the problem is solved At this point you re still not ready to write the program but you can satisfy the urge to see something by creating a prototype A prototype is a very simple preliminary version of the program By designing a few user interfaces you can help clarify your own thinking as well as using the prototype to show the user what you are thinking and facilitate discussion The Prototype The nex
36. esting OS GUI Hardware IB Computer Science Stage A Analyzing the Problem The chart above becomes clearer with a brief look at a specific example This example is only a very brief overview NOT a sample dossier The School Attendance Tracker Students have learned about files and arrays and methods before starting on the dossier So their first thoughts are probably along the following lines e We can start with an array of all the student names e The teacher must choose the names of absent students e When finished a method runs to save the absent names e The absent names must be stored in a file Let s stop now because this is the wrong way to start We have started immediately thinking about the solution the program You will certainly have this sort of thing in the back of your mind but it should not be your focus at first Start by focusing on the problem especially as it relates to the user What s the problem And who cares The problem isn t taking attendance or using an attendance program but rather managing attendance Students miss school for various reasons illness field trips dental appointments meetings with counselors etc Then someone e g the teacher needs to record the absence someone else records the reason e g a clerk schools want to know why a student was absent So there are two intended users teacher and clerk And a vic
37. eve 10 or more mastery aspects Examples here are some links to sample dossiers ideas etc Starting Simple http ibcomp fis edu projects quickAndSimple html Topics for a School http ibcomp fis edu projects TopicsForMe html TicTacToe Prototype http ibcomp fis edu projects newproj TicTacToePrototype ppt Adding Machine Prototype http ibcomp fis edu projects newproj AddingMachinePrototype ppt Stage A Checklist http ibcomp fis edu projects stageAchecklist pdf Average Stage A http ibcomp fis edu projects onlinegrades analysis pdf Better Stage A http ibcomp fis edu projects newproj DocsAF pdf SL Sample Dossier http ibcomp fis edu projects quizTacToeDocs pdf HL Sample Doss http ibcomp fis edu Projects StudentSample2007 pdf IB Computer Science Stage B Detailed Design For Stage B of the project you must produce a plan for Data Structures Algorithms Modules that you will be need in your program Start by reading the goals and the user stories from Stage A Look at specific words and then 1 Nouns for Data structures Variables NOUNS represent data items or data structures The little things are data items Collections or lists are data structures For example a name is a simple variable but a list of names is a data structure probably an array Ifa list is permanent it needs to be stored in a file 2 Verbs for Algorithms Methods VERBS represent things to do algorithms When you ide
38. guide movies CD s e Sports statistics planning tournaments e Parents business varies with the student Graphics Graphics make things more interesting There are plenty of images available on the web But avoid animations cannot show these on paper and avoid highly technical work like image filters unless you are a very strong math student How about a math graphing program Graphics can be a part of any solution like including some nice pictures as long as they are not animations Internal Assessment Dossier Dave Mulkey Germany June 2008 12 32 Some Warnings Parents Business Many students try to do something for their parents especially their parents business Parents are willing helpers and generally available The student might even have a working understanding of their parents business Unfortunately real businesses have computing needs that generally exceed a student s programming skills And some businesses have legal or ethical restrictions that don t really allow them to use a program written by a student Interesting Problems Many interesting problems such as E mail playing chess and video games can be unsuitable for the because e the problem is too difficult for the same reason it is interesting e interesting problems can be difficult to limit and or clearly define e they may be quite difficult to document properly Interesting problems certainly increase motivation However teachers
39. he same convention all the time If you decide to name single variables with singular nouns and arrays with plural nouns int age int ages then do it that way all the time e Readable your code should be readable for the teacher for the moderator and for YOURSELF Use indentation comments understandable names etc You are expected to make your code as readable as possible If you re not sure ask your teacher to read it they ll tell you whether it s clear or not There are no rules but the program must be easy to read Internal Assessment Dossier Dave Mulkey Germany June 2008 27 32 C2 Handling Errors The dossier must document many error handling facilities Guide p 60 For full marks The student fully documents the error handling of each input and output method within the program Guide p 60 This does not mean that every possible set of input data must be documented but there should be numerous descriptions covering all the input and output methods The student need not document the try catch error handling in inputInt and other IBIO methods But if a vaildatedInput method is written for a specific data value this should be documented The explanations can be brief For example Teacher saveAbsences Uses standard try catch commands to handle IOExceptions When an error is detected an error message pops up in an output window This might happen if the user has removed an ex
40. her programs may benefit from conversions of scientific units money units etc where a list of conversions is stored in a file e On Line Help Instructions Most programs can benefit from some on line help This could be stored in a data file with help instruction text stored together with key words providing contextual help e Log File In a tutorial on line quiz situation store results best times best scores etc Print error messages and warnings into a log file instead of on the screen Store passwords and ID numbers in a file In each case the resulting data file must be manipulated and used in a meaningful way IB Computer Science Stage A 1 to 2 weeks 5 10 hours These steps needn t occur in exactly this order but more or less Partial incomplete and revised documents should be preserved for inclusion in the appendix of the final project Follow these steps and take notes Idea Problem State the problem and describe some of the details of the problem Include an outline of existing systems as well as describing some intended improvements over existing systems Step by Step Find a User Find a user who is interested in the idea Collect information and sample data Help the user to describe tasks and scenarios and encourage him her to think in more comprehensive and precise terms Scenarios Write down scenarios stories describing various situations with a variety of results This sho
41. in a format accessible by the attendance modules It name class teacher may be possible to do this from directly inside the scheduling system in C date excuse which case this module will not be part of the attendance program If that s not possible then something will need to be written here Keep in mind this is only a simple unfinished version a real dossier would contain more information and be considerably more complex IB Computer Science Stage B Item Extraction Step by Step 3 4 weeks 10 15 hr From scenarios and goals extract nouns and verbs to find data items data structures and processes needed Tasks Outline gt Program Outline Write an outline of the tasks the user will be able to perform could become Menues Under each task list the modules needed for each task Modules include algorithms data structures and objects classes Object Model Make a list of objects classes needed Break down the objects into these members User Interface Events Actions gt with reference to specific methods and algorithms Data gt properties and data structures should be mentioned Name each member and provide a brief description of its purpose Supervisor Approval Obtain approval before proceeding further Data Structures Design Data Structures to accommodate data storage needs of designed objects Be sure to include sample data and storage needs size as well as diagra
42. ma ao be ee ow ce eae ean ily Crewe pscesises sisasousenbutsibiadeceeenssebeuunnsad uininsuns seen cecoseubatu Sniseshesosubed ssesdjeta si nianaeesoss bectoubesia sinscoseusseusconsainidimecoess 1 Donald Duncan inaqaoun bedsvee onuenous nnanusseces svat oeuneaussanuesooes sees suounenn buasequenss soscssoundpateansensees nics ieouunsnsuansauesss soesoeeuennnaaauaaaees Students should also collect other kinds of information like rules teachers must take attendance in the first 5 minutes of class difficulties paper grade books cannot be shared with the office This type of information can appear as quotations or summaries of discussions with the user These can be recorded as user stories Internal Assessment Dossier Dave Mulkey Germany June 2008 6 32 A Systematic Method For maximum marks in section Al Analyzing the Problem the student must provide evidence that a systematic method has been used in the analysis of the problem Guide p 55 A systematic method is one that takes into account what input and output will occur and what calculations and processes will be necessary to obtain the desired output Guide p 55 A simple systematic method that emphasizes user discussions and users needs is collecting scenarios or user stories XP or use cases UML The student must take notes during user interviews and then extract stories about things that happen and tasks the user performs The student sh
43. mers to go back to previous stages Spiraling back is inevitable but students should do this consciously rather than working in an unstructured and undirected fashion Students should always have a clear sub goal in mind when they are working Are they testing Developing Designing After the analysis and design phases are finished students should be implementing the program to meet the goals not changing goals to make the programming easier As the program becomes large and complex and bugs are difficult to find adding required features becomes difficult so instead of doing required work students may create a new goal that is easy to implement Clever gadgets and cool interfaces disappearing buttons graphical decorations etc probably contribute nothing to the original goals If done sensibly spiraling back to change the original goals would result in a significant rethinking of the design Starting over is the extreme case of spiraling back and it demands a complete redesign avoid this whenever possible B Computer Science Internal Assessment Dossier Dave Mulkey Germany June 2008 32 32 1 Guide Computer Science First Examination 2006 IBO Geneva 2 XP http www agilealliance com system article file 1006 file pdf Extreme Programming the Oak Grove Way Steve Mitchell Oak Grove Systems 3 UML http www visualcase com tutorials use case diagram htm Artisto Visual Case 4 McConnell After the Gold
44. ms to clarify non trivial structures Clearly explain files arrays and ADTs including the reason for using them New ideas may arise and require further algorithms to be added to the object model above Internal Assessment Dossier Dave Mulkey Germany June 2008 22 32 Algorithm Details Design algorithms including clear detailed explanations of how algorithms will function This may include pseudo code and Java code snippets to clearly explain the intended programming Complete method headers must be written but pseudo code needn t be as precise as Java code Standard algorithms may be identified by name e g execute sequential search Non standard algorithms must be described in greater detail Java test code may be written to test feasibility but explanations should not be presented as finished Java code Refinement It s likely that students will go back and forth between Modules Algorithms and Data Structures rather than proceeding in 3 separate steps New ideas for criteria for success may occur e g reorganizing files use of other hardware etc These can be integrated into the original goals document as long as important user oriented goals are retained Mastery Factors Your design must include clear reference to the mastery factors that will be demonstrated For example if one of the data structures is a RandomAccessFile and there are methods for saving and searching then that covers 2 mastery items
45. n below This is a preliminary step which need not appear in the finished dossier so feel free to do it on paper You might want to include these rough notes in an appendix Bold noun variable or class brackets list arrays and or files or classes italic verb task or method CAPITALS values constants final in Java Internal Assessment Dossier Taking Attendance User Story At the beginning of each class the teachers take attendance They mark down the names of any absent students If a student arrives late they change the attendance to LATE instead of ABSENT This is messy when done on paper requires using pencil and an eraser Input name of absent student period of class meeting name of class Processing At the end of the day names of absent students must be sent to the office This is currently done on a standard form Output list of absences sent to office Excuses User Story When students return from absence they must bring a signed note to the office The attendance clerk then writes EXCUSED next to the student s name in their book of absences If a student forgets the note the clerk ca s the parents at home If the parent says the student was not sick the clerk writes UNEXCUSED Input note or message from parents Processing decide whether the absence is excused or not Storage write excused or unexcused in the paper register
46. n issues in the problem domain that you don t understand Let them make decisions for you or let them help you make decisions Sample Data Students are required to show evidence that relevant information has been collected Guide p 55 Questionnaires certainly satisfy this requirement A simpler way is to collect sample data as it exists in the current solution often on paper If teachers are doing their attendance in a paper grade book make a photocopy and include it in the dossier Armand oye Vays E A ACTEN s ty 6 bry Vere Teacher s Paper oat _ to Attendance Record a i siy E oS ea i eee e H y i rs oe a i AES i tee ii IB Computer Science More Sample Data A single photocopy probably doesn t contain enough sample data to enable the student to analyze the problem fully Most likely the school already has an attendance system whether paper based or electronic They probably print some kind of reports Get copies of some sample reports discuss them with the user and include them in your dossier Looking at actual reports and actual data helps focus your thinking Attendance Summary Entire Year Student IO LOE Attendance Days Abrent Days Teta Daye eso4aniisses O da o d O3 Ee 6 do d5 O a aS 691005115141 20 b90219115513 d esosidiisas 4 Daily Attendance Report Gilbert Cabot Davis Copperfield Dani en ats a a
47. ntify an algorithm try to link it to a data item or data structure For example rather than search it should be find a name in a file or find a name in the names array Try to group the algorithms together with the data structure s affected in the same class When possible include parameters pre conditions post conditions and results return values 3 Modules Classes Once the data structures and algorithms are identified GROUP these together into cohesive modules classes Cohesive means the ideas belong together In a program for a video rental store the customer database should be separate from the video database and these should form separate classes The task of renting a video will use both of these classes but it should be in a third class e g the cash register class Internal Assessment Dossier Dave Mulkey Germany June 2008 15 32 What Order to Do It You can develop these ideas in any order You might try to list all the data structures first then add the methods to the data structures and finally group data structures into cohesive classes But you probably won t think of everything the first time around so you will go back and add more If you can think ahead and object oriented programming OOP makes sense to you you might start with the classes rather than starting at the data structures end Classes correspond roughly to areas of the problem solution In the video rental store the customer
48. o they quit long before they have covered all the necessary algorithms e There is just too much to write too many algorithms This comes as a bit of a surprise as students think of more and more algorithms each time they write an algorithm If the list of algorithms starts growing explosively it s a hint that e the problem might be too difficult OR e the attempted solution is too complex and overly ambitious OR e the student is programming inefficiently adding new code for each new idea rather than writing re usable methods see page 10 OR e all of the above Unfortunately by this stage it may be too late to choose a different problem But it s not too late to design a more efficient and less ambitious program As a famous scientist said Make it as simple as possible but not simpler Albert Einstein Re usable methods make things simpler use them lots and lots Internal Assessment Dossier Dave Mulkey Germany June 2008 20 32 B3 Modular Organization In OOP modules are normally classes Classes correspond to real world objects An OOP Object usually represents a combination of data and algorithms These can be extracted from user stories and goals This could be done first before data structures and algorithms guided by the Prototype and Goals Or it can start with a very simple version and expand as more data structures and algorithms are described A preliminary version can be written as
49. om your teacher If you get stuck spend 20 minutes or so trying to figure out what s wrong After that you should stop working and ask your teacher for help Don t waste hours searching in vain If you re at home wait until the next day at school Spend your time on something else work on a different module do homework for another class clean up some documentation etc Don t get trapped in a stubborn cycle of unproductive wasted time IB Computer Science Naming Convention The following web site presents a recommended Java Style Convention http geosoft no development javastyle html Here is a summary of the most significant points e Classes have Noun names and start with a Capital letter TeacherInterface AbsenceRecord e Variables have noun names starting with a small letter age names thisAbsence e Methods have VERB names starting with a small letter sortNames enterExcuses e Constants are in ALL_CAPS with underscores between words final String UNEXCUSED Unx e Use CamelCaps for multi word identifiers capitalizeEachNew Word e Local variables have short names for int x 0 x lt 5 x 1 e global variables have long names several words String defaultDataPath d attend e Use get and set for data access methods in classes gt x There are lots more recommendations The most important points are that the code should be e Consistent use t
50. ot strange error provoking situations nor multiple examples of the same feature Targeting Criteria for Success A set of sample output should document successfully meeting the criteria for success A2 This must be comprehensive It must include ample normal data to show the completeness of the solution e g lists of data rather than just single data items sample data files with ample data as well as abnormal data to test the robustness of the solution e g proper responses to error conditions It must be possible for the teacher to perform these tests or to sit with the student while they do so Internal Assessment Dossier Dave Mulkey Germany June 2008 31 32 Usability and Error handling Some of the sample output above will demonstrate usability and error handling The annotations should reflect what is demonstrated in each case These may also be referenced by sections C2 and C3 Evaluating Solutions See notes in IB assessment criteria Be sure to address the criteria for success and make suggestions of how a future version could expand these criteria Final Interview A 30 60 minute interview with the teacher after the teacher has seen the documentation helps the teacher with the assessment The teacher should award a holistic mark and sign the cover sheet Final Comments The 4 stages appear to represent a straight line process but we know that bugs mistakes bad decisions and uncertainty cause program
51. ould highlight items in the stories that involve input output processing and storage Here are some user stories about the attendance system Taking Attendance User Story At the beginning of each class the teachers take attendance They mark down the names of any absent students If a student arrives late they change the attendance to LATE instead of ABSENT This is messy when done on paper requires using pencil and an eraser Input name of absent student period of class meeting name of class Processing At the end of the day names of absent students must be sent to the office This is currently done on a standard form Output list of absences sent to office Excuses User Story When students return from absence they must bring a signed note to the office The attendance clerk then writes excused next to the student s name in their book of absences If a student forgets the note the clerk calls the parents at home If the parent says the student was not sick the clerk records unexcused Input note or message from parents Processing decide whether the absence is excused or not Storage write excused or unexcused in the paper register IB Computer Science Internal Assessment Dossier Weekly Summary User Story In the current paper system the attendance clerk has a paper list of all the student names Each time a student is absent the clerk places a mark next
52. pful And choosing yourself as the user is a bad idea forbidden Internal Assessment Dossier Dave Mulkey Germany June 2008 11 32 Suggested Topics What is a good topic area Many students have written successful dossiers in many different topic areas over the years Data Base Oriented Problems The most common choice is a personal database storing something like phone numbers or web addresses This has an obvious need for file handling so it s easy to fulfill the HL and SL file mastery factors It also corresponds well with syllabus topics Contrast this with communication oriented problems that require skills and techniques that are not in the syllabus A common difficulty in Data Base dossiers is a lack of data Student programmers are reluctant to actually type in lots of phone numbers so they end up with a program that is difficult to test they test it only on a few data entries Another common difficulty as lack of excitement Data Base dossiers can easily become boring and the student loses enthusiasm Still a Data Base dossier is an easy choice there are lots of possible topic areas CD collections video collections e mail addresses etc and the solution is usually straightforward Something more exciting It s pretty easy to dream up exciting problems like making a web search engine or a chat server or a 3 D ego shooter game But if it s really exciting it s quite likely to b
53. rnal Assessment Dossier Dave Mulkey Germany June 2008 17 32 Presenting Your Design Stage B Detailed Design requires a design in 3 sections B1 Data Structures B2 Algorithms B3 Modular Organization Some students want to work in a top down fashion designing classes first and then breaking them down as shown above left Others wish to work in the order specified starting with data structures then adding needed algorithms and organizing it all into modules as the last step Most people think about many things at once data structures then algorithms then back to data structures then invent a class etc Most students will find it productive to set a clear goal like list all data structures and write something down then work on another goal If you try to do it all in your head you are likely to get lost and confused and waste lots of time starting over Be sure to produce lots and lots of rough notes and keep them to include in the appendix However you do it be sure to read the Assessment Criteria carefully and include all the required pieces The following are common mistakes possibly forbidden from student dossiers that result in lost marks e B1 missing diagrams missing sample data e B2 code copied from the finished program instead of writing pseudo code forbidden missing pre and post conditions e B3 missing connections to data structures Sample Design for Attendance Applic
54. s refer directly to the IBO Guide and TSM at p 30 IBOGuide Syllabus http occ ibo org ibis documents dp gr5 computer_science d_5_comsc_gui_ 1005 1 e pdf Teacher Support Material Internal Assessment _http occ ibo org ibis documents dp gr5 computer_science d_5 comsc_tsm_0809_ 1 _e pdf Internal Assessment Dossier Dave Mulkey Germany June 2008 1 32 Table of Contents The Dossier Four Stages Planning Before Doing diagram Software Development Stage A Analysis p5 Problem User Sample Data Systematic Method p9 Prototype p10 Automation Keeping it Under Control p11 Choosing a Problem Suggestions p14 Stage A Step by Step Stage B Detailed Design p15 What Order to Do It p16 Attendance Example Extracting Words p18 B1 Data Structures p19 B2 Algorithms p21 B3 Modular Organization p22 Stage B Step by Step Stage C The Program p23 Iterative Development p23 Functional Prototype p25 Mastery Factors p25 Alpha Version p27 Naming Convention p27 C2 Handling Errors p28 C3 Success of Program p29 Stage C Step by Step Stage D Documentation p30 D1 Hard copy Output p30 D2 Evaluating Solutions p31 Stage D Step by Step IB Computer Science IB Computer Science Dossier Overview Start Here Problem Document The dossier is the Internal Assessment component of IB Computer Science HL and SL This is much more than a simple Java
55. s are clearly a separate area from the videos so it is easy to think of a customers class and a videos class In any case you probably need several iterations in the development process jumping around from data structures to algorithms to classes You can start by making simple lists without worrying too much about organizing the lists Then take your lists and start grouping things together putting algorithms together with data structures and grouping them roughly into classes Your prototype interfaces might help you with discovering classes Once everything is listed and grouped start adding details parameters for algorithms sample data pseudo code for algorithms and diagrams for data structures and class relationships Most people will think about many things at once data structures then algorithms then back to data structures then invent a class etc Most students will find it productive to set a clear goal like list all data structures and write something down Then work on another goal Write things down but DON T start programming If you try to do it all in your head you are likely to get lost and confused and waste lots of time starting over Be sure to produce lots and lots of rough notes and keep them to include in the final documentation IB Computer Science Attendance Example Extracting Words Start out by highlighting nouns and verbs two different colors in the user stories and goals as show
56. set goals criteria for success The problem needs to be specific and the goals should address the needs of the intended end user Starting with a solution e g T ll write a game rarely addresses a specific problem or a specific user The Guide says The dossier must address a single problem that can be solved using computer systems and which has an identified end user Guide p 52 B Designing After a thorough analysis produces appropriate goals a thorough and careful design should make the programming task relatively straightforward avoiding wasted time and effort when programming Stage B Detailed Design data structures files arrays Abstract Data Types algorithms methods and pseudo code modular organization classes data structures methods The Guide notes with stages B and C it may occasionally be necessary for students to return from C to B one or more times to refine their detailed design in a spiral of design and development Guide p 53 So although students should devote significant time and effort to creating a good design they needn t worry about making it perfect Internal Assessment Dossier Dave Mulkey Germany June 2008 3 32 C Programming Students are expected to write a substantial program 500 3000 lines Guide p 54 this is only a suggestion not a requirement The program should fulfill the Criteria for Success goals written in Stage
57. sh 7x Shakey W 01 Sep 2008 Sick Exc Eagle Eddie English 10a Cho K 02 Sep 2008 Skip Unx Adams Alice ath 10a Einstein A 01 Apr 2008 agle Eddie ath 10a Einstein A 01 Apr 2008 In a sequential text file it would be difficult to change the the program must load the entire file into an array make changes and then rewrite the entire file A RandomAccessFile will be used so that changes are easier IB Computer Science Internal Assessment Dossier Dave Mulkey Germany June 2008 19 32 B2 Algorithms Notice that parseStudentName didn t come from a user story and it xK e 6c _ a S Now that the data structures have been designed concentrate on the Po M E T DOES 1 A a pes ae a oe algorithms needed for those data structures Also design algorithms that oie eae a aE pions nes es ae Hs P aie perform actions indicated in the prototype look at that again BO eee Ot OE OE Ae LRT EDUT MEOLA loadClassList classID ia vag sree eae t pre condition class list files exist for each classID post condition all absences have been copied into central Absences S file and all the teacher absence files have been deleted post condition name list box contains student names return nothing return nothing open AllStudents file masterFile open Absences central file loop through entire file String files createListOfFiles server absences info file re
58. should provide guidance when the students are selecting topics They must ensure the topic has reasonable scope for complete coverage of the required mastery factors and that the problem is not too difficult In many cases it is sufficient to help the student find a reasonable way to limit the scope of the problem and solution Unlimited High school students won t succeed in making general purpose commercial software similar to a professional word processing program as they have neither the time nor the necessary skills It is better to address a very specific and limited problem Rather than writing a word processor the student could create a program that analyses essays by counting words and producing an index of overused words Even if this is only usable on text files not doc files it fills a real need without being too large or too complex Still the solution should not be overly simplistic Keep the problem relatively simple but produce a really good solution IB Computer Science Intended End User There must be a specific intended end user This must be a real person or people other than the author This requirement causes some discomfort for many IB Computer Science students but they must overcome their discomfort early and engage in productive discussions with the intended user during the analysis and design stages If done correctly this makes the programming job easier Avoid the following e Don t say my progr
59. t page shows a prototype for the attendance problem Certainly other prototypes are possible this is just one example Also it could be considerably longer and more detailed but it s kept simple here for brevity Students are encouraged to produce these sample screens with a word processor or presentation tool if they prefer pen and paper that s acceptable Then discuss the prototype with the intended user s The prototype solution must be preceded by an initial design for some of the main objectives Guide p 56 So the diagram above at left must be created before the prototype Also the prototype should correspond to the initial design assessment A3 So DO THE DESIGN before the prototype If you prefer your design could be a text outline or a UML diagram IB Computer Science Teacher Taking Attendance Classes Internal Assessment Dossier Date 01 Apr 2008 Data File Teacher Einstein A Prototype ewes Students Absent F Dave Mulkey Germany June 2008 9 32 ters Paul English 9c Elliot R 31 May 2009 Peters Paul Math 9c Gauss M 31 May 2009 Adams Alice Math 10a Einstein A 01 Apr 2009 Math 9a a Alice PF an Bobby Math 10a Baker Bobby agle Eddie Math 10b Cho Kim Math 11 Duck Don Eagle Eddie The teacher clicks on a class the list of students appears The teacher clicks on each absent student each name is
60. tailed Design IB Computer Science Choosing a Problem and a User What is a bad choice for a problem The attendance system is a bad idea for an IB dossier because e it involves lots of users and that makes everything more difficult e the school s administration will probably want it to integrate with some other software like the scheduling software that s difficult e the other software probably has requirements and security restrictions that are beyond the student s control and expertise e it probably doesn t really need a solution anyway Students should avoid problems that require exotic tools and techniques like e web communications e real time systems controlling a robot e unusual hardware like sensors and wireless communication e video animation because it cannot be represented on paper Systems that the student cannot control cause problems e aPC is easier to control than a server e data files are easier to control than large data base systems e the school is a better environment than real businesses having legal or ethical restrictions like a doctor s office or a factory There are no bonus points for choosing an unusual topic so Keeping It Simple is the advantageous but do try to choose something interesting What is a bad choice for a user Whichever user works with your chosen problem is a good one but if possible choose an experienced competent user they will be more hel
61. te information from the user The student needs to search for missing information and go back to the user to collect any information or data that are missing Through repeated discussions the student develops a thorough understanding of the problem Dave Mulkey Germany June 2008 7 32 Choosing Goals Criteria A2 is about Criteria For Success also called objectives or more simply goals Some goals seem obvious e the computer must store the attendance record for each student But even obvious goals sometimes need clarification e the computer must store an attendance record for each student during each period of each school day so 6 records per day Other goals are not so obvious They can be suggested or clarified during user discussions e the attendance clerk needs access to ALL teachers data so she can follow up and collect excuses the next day e the vice principal needs a weekly report of students who have been absent very often so he can chase down chronic offenders e teachers do not wish to type in student names but rather should be able to select them from a list by clicking so taking attendance is faster and names are not misspelled The student relates all of the objectives of the solution to the analysis of the problem and outlines the limits under which the solution will operate Guide p 56 This implies that there are reasons for the goals The reasons so needn t be long and complex
62. ternal hard disk or specified a non existent directory or lost a network server connection They can correct the situation and then press the Save button again Clerk inputExcuse returns String inputExcuse uses a loop to input and validate an excuse String If the user types a valid excuse in the list Exc Unx Tdy the value is returned Otherwise they must try again This guarantees that no misspelled excuses are saved in the AllAbsences file Some students like to copy Java code into this section to show how the error handling works That is acceptable but not necessary In any case written explanations are still required In some cases screen captures might be helpful here but generally the explanation is sufficient This section may also use references page numbers to output provided in section D1 IB Computer Science Internal Assessment Dossier Dave Mulkey Germany June 2008 28 32 C3 Success of the Program A complete sample run should show all the features of the program executed as might happen in a single session or several consecutive sessions For the attendance application it could contain two teachers taking attendance for several classes Evidence here refers to hard copy output in criterion D1 print out the resulting data files the clerk collecting the absences print out part of the resulting AllAbsences file print the daily summary report clerk enters excuses
63. the user needs without causing problems or increasing the user s workload The prototype above demonstrates the essential features as requested by the users Now the user might have further questions or suggestions e Do I need to type text for the excuses or can I have a drop down list e How will the computer know the names of the students in my classes Do I need to type them in or is it automatic e The vice principal would really like automatic notification when a student has missed 10 days of school Could we add a button on the clerk s page that displays the students with too many absences e Can we have pictures of students so the teachers can take attendance more easily in the first week of school Users often ask for automation They don t want to spend all day clicking buttons waiting for processing and then reading the results They want as much automation as possible Happy Programmer Reasonable Expectations After showing the prototype to the end user s e g the clerk and some teachers the programmer might decide to add another file or files to the program containing the entire schedule of all the students and all the classes in the school this is needed to automate the teachers page Once this data is added the programmer might be tempted to add a scheduling module to the program to make it even more useful And pictures of the students and a web interface and some small games to make the
64. uld be fairly comprehensive covering many aspects of the problem but needn t be complete This might be done in conjunction with the user or written first and then discussed with the user Initial Design Make a data flow diagram showing data files and user interfaces and outlining typical interactions Use PowerPoint or a word processor Prototype Produce mock ups of user interfaces inputs and outputs and list of data storage requirements This should be fairly complete but need not be very detailed User interfaces shown here are more a basis for discussion than an actual commitment to a specific appearance or functionality Goals Meeting Show prototype to user Check that the prototype is consistent with the scenarios Sit together and write a list of goals features and limitations Internal Assessment Dossier Dave Mulkey Germany June 2008 14 32 Criteria for Success Write Criteria for Success based on mock up and goals This document serves a central role throughout the project Be sure to include e Features especially automation e Usability requirements e Reliability requirements e Limitations Get user approval and supervisor approval for these criteria Supervisor Approval Obtain supervisor approval before proceeding to the design phase The supervisor should ensure that the choice of problem and goals are neither too easy nor too difficult there must be sufficient scope to achi
65. users happy and and and oe Be WARC CRCCPING FEATURISM Internal Assessment Dossier Dave Mulkey Germany June 2008 10 32 Keeping it Under Control The user s needs and wishes for automation lead to an expansion and usually complication of the solution The programmer s needs to solve the problem and meet a deadline drive the solution in the direction of simplification Young inexperienced programmers tend to add more code to for each feature added to the solution This generally leads to unfinished software didn t meet the deadline or unreliable software met the deadline but didn t really meet the goals In a successful dossier the student can keep the drive for expansion under control in two ways e choose goals and features carefully providing only what is needed e good programming techniques that simplify the program but simultaneously increase it s flexibility and power Schematically it looks like this Program Growing Wishes with and Features re usable modules By using reliable programming techniques to create re usable classes methods and data structures the programmer can create a flexible system Then the features and usability of the program can grow faster than the size of the program There is less to write less to debug and a bigger chance of success This may sound magical but it only requires careful design That s the reason for Stage B De

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