How do engineering students without a strong knowledge base
Contents
1. Prior knowledge strong weak Direct instruction eo Student knowledge brought to the task A activation at start of task Inert learning Meaningful can be recalled when learning asked for but is not tivation spontaneously applied uhe applied to the k spontaneously task tasks Interpretation of the purpose of the task Complex problem space Problem solving skills Habits of mind Figure 10 Revised model of task based learning Meaningful learning spontaneously applied to other tasks 4 activation during task Inert learning can be recalled when asked for but is not applied to other tasks What is shown tentatively in the revised model in Figure 10 is an area that needs more work the interface between meaningful and inert knowledge How is inert knowledge activated and made meaningful as the student begins a task How is further inert knowledge activated and made meaningful during the task as a student suddenly recalls a key piece of information that he or she had not considered before Why is knowledge that is meaningful in one setting left inert in a different yet similar setting The considerable body of literature on transfer of knowledge will no doubt shed some light on this yet it would be useful to consider this question in the context of task based learning where students are presented with a series of different yet related tasks2. Introduction to Electrical and Computer Engineering at Oregon State University They were engaged in a project based lab which involved the TekBots robotic platform http eecs oregonstate edu education tekbots html where the problem required application of knowledge of electrical systems to a series of projects as students built the robot platform learned how it functioned and created a bump bot designed to back up and turn around after it bumped into an object Seven case studies were selected from a pool of volunteers and comprised students who scored at the low end and at the high end of scores on a survey of electrical concepts given on the first day of the lecture portion of the class The survey developed by the researcher consisted of a set of questions on DC circuits from the concept test described in Mazur 1997 and questions drawn from McDermott amp van Zee 1985 and Shipstone 1984 Each question showed a diagram of a circuit and asked students to make one or more predictions about the circuit Students selected from several possible answers and wrote an explanation of their choice in the space provided The questions were scored 2 if the student chose the Bledsoe Electrical engineering students concepts and reasoning correct response and gave a correct explanation 1 for a correct response with an incorrect explanation and O for incorrect or missing response and explanation Figure 3 shows an example of a question
3. This perspective was valuable for this study as traditional accounts of reasoning do not support conceptual change Nersessian 1992 argues for an explanation of conceptual change through the problem solving process noting that records of this process capture processes that comprise model based reasoning Chi et al 1989 and Chi 1992 employ a similar approach using student self explanations and think aloud methods as a means of tracking student reasoning and conceptual change Reasoning and conceptual change are in this model intertwined and reasoning consists largely of the application of current concepts to a specific problem Findings Two of the case study students began the course with low prior knowledge While it might be expected that students with low prior knowledge would not perform as well as students with high prior Knowledge in a task based setting the results as exemplified by these two students were not that simple Subject AM was male age 19 AM had studied electricity in a prior physics course and had built his own computer so he had some prior knowledge of electrical concepts and electronics However out of a possible score of 24 on the survey AM scored 6 The highest math class that AM had taken was MTH 252 Integral Calculus Subject MJ was female age 23 MJ could think of no prior courses where she had studied electrical concepts and had no prior experience with electronics Her score on the initial su
4. student learning mental representations conceptual change and reasoning as students struggle with solving problems and completing tasks as well as the dynamics involved in the social construction of knowledge The results of many studies around these questions may then be compared with studies involving similar questions about students learning by didactic methods Research Questions This study was developed to help fill the gap in knowledge about how students and reason within task based learning contexts Specifically this study examined learning and reasoning among first year electrical engineering students as they worked to complete tasks and solve problems in a project based lab component of one of their required courses The questions guiding the research were 1 What phenomenographic categories of common knowledge regarding direct current electrical circuits are constructed by first year electrical engineering students 2 What relationship exists between a student s prior conceptual understanding of electrical circuits and the student s reasoning processes while solving problems involving circuits 3 How does a student s meaningful learning change as the student grapples with a series of complex problems This paper will look specifically at two students who entered the course with low prior knowledge A Proposed Model Whitehead 1929 proposed a model of learning within a task based setting The knowledge that a studen
5. Hmelo C E 1998 Problem based learning Effects on the early acquisition of cognitive skill in medicine The Journal of the Learning Sciences 7 173 208 Mazur E 1997 Peer Instruction A User s Manual Upper Saddle River N J Prentice Hall McDermott L C amp van Zee E H 1985 Identifying and addressing student difficulties with electric circuits In Walters R D amp Rh neck C eds Aspects of Understanding electricity Proceedings of an International Workshop Ludwigsburg Institut fur der Naturwissenschaften and der Universitat Kiel Nersessian N J 1992 How do scientists think Capturing the dynamics of conceptual change in science In Giere R ed Cognitive Models of Science Minnesota Studies in the Philosophy of Science 15 pp 3 44 Minneapolis University of Minnesota Press Nersessian N J 1998 Model based reasoning in conceptual change In Magnani L amp Nersessian ed N J Model Based Reasoning in Scientific Discovery pp 5 22 New York Kluwer Academic Osborne R amp Freyberg P 1985 Learning in science the implications of children s science Aukland and London Heinemann Saunders K Mclntosh J McPherson J amp Engel C E 1990 A comparison between University of Newcastle and University of Sydney final year students Knowledge and competence In Noonan Z M Schmidt H G amp Ezzat E S eds Innovation in medical education An evalutation of its present sta
6. It is probable that the students interpretation of the purpose of the task enters into the activation process as the student decides What is to be done here and what do need to know in order to do it Habits of mind emerged as students revealed their attitudes toward the course and approaches to learning Both AM and MJ entered the course with little prior Knowledge but relatively high math ability MJ was about a year ahead of AM in her math coursework but AM had more prior experience with electricity and Bledsoe Electrical engineering students concepts and reasoning electronics Thus both appeared to be on equal footing as they began the course Both spent the majority of their lab time on task working steadily on their lab assignments However conversations revealed some striking differences MJ s conversations were largely around the lab topics She tended to work with a lab partner and both she and her partner worked together to understand the concepts in lab and to apply concepts learned in class to lab MJ frequently asked the teaching assistants for help or for confirmation of her ideas AM s conversations with his usual lab partner were frequently about topics other than lab even while working their way through the lab activities AM and his partner worked together when the activities required them to but separately when they did not While AM asked the TAs for help he did so less frequently than MJ Talk about the
7. a means of teaching reform Because of the high costs of developing and implementing task based curricula educators may want to know whether the methods are truly advantageous and whether there are any disadvantageous effects However the question Does task based learning improve test scores may be the wrong question to ask At the very least it is overly simplistic Task based learning is a very different way of learning from traditional lecture practice test teaching and creates different cognitive demands It is reasonable to hypothesize that Bledsoe Electrical engineering students concepts and reasoning students engaged in task based learning may be thinking reasoning and experiencing conceptual change differently from students in other learning contexts Capturing these differences is often difficult as conceptual models and reasoning skills require more than a standardized test or a survey to measure Furthermore any discussion of generic students is oversimplified as student enter a task based course with a wide range of prior Knowledge and reasoning skills They often work in groups where the collective knowledge allows the group to achieve tasks of greater complexity than any one member could achieve individually A better question to ask then may be How do student learn content knowledge and reason with that content knowledge within task based contexts Answering this question requires a rich description of
8. and voltage and some seemed to believe that voltage was a measure of some quality of current or of current itself 4 Voltage is pressure or push This concept was used in the lecture notes as an analogy to help students understand voltage While not strictly scientifically accurate it served as a useful model as students made predictions about their lab tasks and the interview tasks This may have been drawn from the water pipe analogy since the class notes compared voltage with measuring pressure in the pipe 5 Voltage is potential energy This concept while more scientifically accurate was the most difficult for students to understand Those who described voltage as potential energy either used the push concept to make predictions about where current would flow or discarded the idea of current entirely and described circuits in terms of mathematical relationships In the initial interview AM seemed confused by the concept of voltage and tended to describe voltage in terms that he also applied to current Though he wasn t fully satisfied with this explanation he nevertheless went back to it as he struggled to define the term For instance you measure voltage in lab AM Right So what do you picture yourself measuring AM long pause The number of electrons at a give moment Looks back at interviewer Okay So when it says it s such and such volts or when you measure so many volts across a resistor
9. class that went on between AM and his partner was frequently negative and AM appeared discouraged by the rigor of the course and his performance on exams The self perceived success of these two students may have been related to their differing levels of math but a large part may be attributable to their attitudes toward the course and the student skills demonstrated during the course These factors were not measured directly during the course of the research so conclusions around this must remain tentative but it appears to be an important factor to consider when planning task based learning and evaluating its success Literature cited Albanese M A amp Mitchell S 1993 Problem based learning a review of literature on its outcomes and implementation issues Academic medicine 68 1 52 81 Anderson J R 1987 Skill acquisition Compliation of weak method problem solutions Psychological Review 94 192 210 Bledsoe K E 2007 How Do Engineering Students Develop and Reason With Concepts of Electricity Within a Project Based Course Unpublished dissertation to be submitted to the graduate faculty of Oregon State University Bransford J D Goldman S R Hasselbring T S Pellegrino J W Williams S M amp Vye N 1993 The Jasper Series theoretical foundations and data on problem solving and transfer In Penner L A Batsche G M Knoff H W amp Nelson D L eds The challenge in mathematics and science education p
10. for a definition while her spontaneous explanations involved voltage in its mathematical relation to current and resistance I Okay so what is voltage Mu It s the change in potential from here to here pointing to resistor on diagram or from here to here or wherever you re measuring it from Change in electric potential MJ initial interview MJ They re both getting the same voltage from the battery doing it like this And this way the voltage to each of them can only be equal to the voltage across the battery it can t be and since the resistance of each of them is assumed to be equal then this is this bulbs in series can only get half of the voltage of the battery and this can get the other half But this way bulbs in parallel they can each have the full voltage of the battery MJ initial interview describing series and parallel circuits Primary concept the nature of resistance Like voltage resistance was a difficult concept for all students The class notes in the second week introduced the concept of resistance while introducing Ohm s Law The notes relied on a water analogy comparing wires to fire hoses and resistors to drinking straws forcing the water in a fire hose through a drinking straw slows the flow of water considerably There was also a molecular explanation involving the speed at which electrons can diffuse through materials The target concept in the notes appeared to be oss of kinetic energy However How
11. from the survey 5 Observe the circuit below This circuit contains a dry cell a bulb and two resistors R1 and R2 Ri R2 M Predict and explain the change in brightness if any of the bulb in each of these situations a If R1 is increased the bulb will get brighter get dimmer stay the same c If R2 is increased the bulb will get brighter get dimmer stay the same Figure 3 Sample question from the conceptual survey administered at the beginning and the end of this study and used in the case study interviews Case study students were interviewed early in the term to develop a description of the mental conceptions they held around the concepts of current voltage and resistance During the interview students were given the survey that they had filled out The researcher read each question and noted the student s response then asked if the student still held that view Students explained their responses then were asked to create the circuit using wires bulbs batteries and resistors mounted on a board in order to test their predictions Students observed the results and attempted to explain any discrepancies Students were videotaped at least three times during lab as they engaged with the projects and the researcher engaged students in conversation during lab when practical The researcher also sat in on lectures in order to observe how students were learning concepts and what language the might be expected to use arou
12. model of how students use their prior knowledge to reason within task based learning environments and how in turn reasoning within a task affects their concepts Introduction Task structured curricula are anchored in a task problem or project which requires student to reason across content areas rather than work through an established series of content topics The effectiveness of task structured curriculum has been the subject of a great deal of research most of which has drawn ambiguous conclusions Albanese amp Mitchell 1993 Tests of content knowledge alone sometimes show that students taught in traditional settings have a slight advantage over those taught in a task based setting for example Saunders et al 1990 but in other cases show insignificant differences between the two groups for example Enarson amp Cariaga Lo 2001 Students taught in a task based context often show an advantage in long term knowledge retention Breton 1999 and may also be better able to apply their knowledge to real world problems Vernon amp Blake 1993 Students engaged in problem based learning often show a greater improvement in problem solving skills over their traditional counterparts as might be expected when problem solving was part of the daily problem based learning context Hmelo 1998 Inconclusive results of studies on knowledge outcomes and possible negative consequences have not inhibited the promotion of task based learning as
13. of electrons and to be highly directional Current he described as being used up by bulbs and other elements in the circuit This may be related to the concept of current as the flow of electrons which students often picture as material particles In AM s view current came from the battery where it was stored and traveled through wires to the circuit elements where it was used up How it returned to the battery was not made explicit Resistance involved holding back the material flow of current in some way and the position of the resistor determined what effect it would have on the circuit Compared with the initial interview concept map AM s map for an observation of Lab 2 Figure 5 reveals less attention to the concepts themselves and more to the practical application of the concepts in lab One of the main activities that AM completed in this lab was construction of two circuits one with resistors in series and one with resistors in parallel Students were to measure voltage across all resistors and current through them then calculate the power dissipated In this map AM had altered his ideas about batteries to include batteries as a source of power which AM did not distinguish from current and as a source of voltage By this time AM had measured the voltage of the batteries and was aware of the voltage printed on the battery label At one point during the conversation AM noted that if his partner wasn t getting voltage mea
14. OSU Oregon State Univeasity How do engineering students without a strong knowledge base reason and form ideas about electricity within a task based learning context Karen E Bledsoe Doctoral candidate Department of Science and Mathematics Education Oregon State University Corvallis OR 97331 Instructor Department of Biology Western Oregon University Monmouth OR 97361 http www wou edu bledsoek bledsoek wou edu A paper presented at the Association for Science Teacher Education International Conference Clearwater Beach Florida January 3 6 2007 Department of Science and Mathematics Education Oregon State University Corvallis OR 97331 Bledsoe Electrical engineering students concepts and reasoning How do engineering students without a strong knowledge base reason and form ideas about electricity within a task based learning context Abstract The purpose of this study was to examine conceptions held by first year undergraduate electrical engineering students around the concepts of current voltage and resistance in simple and complex circuits as they enter a task based learning environment and how their prior Knowledge interacted with their reasoning skills as they worked to solve the problems presented in the tasks While the study involved students with both high and low knowledge this paper focuses on two students who entered the course with low prior knowledge The study contributed to an overall
15. affects bulb brightness ebattery supplies voltage ebulb converts electrical energy into light energy current is energy ecurrent is the flow of electrons ecurrent takes the path of least resistance ecurrent is used up by circuit elements eresistance restricts the flow of current eresistance creates load on the circuit From other sources ecan be divided across resistors evoltage drives current ecircuit elements have polarity ecurrent in the wrong direction can damage circuit elements eexcess current melts fuses efuses have resistance Meaningful knowledge 0 a Lo From prior lab and interview ebattery supplies voltage From other sources ebattery loses charge as it loses voltage evoltage is additive across resistors in series enegative current produces negative voltage reading eresistance current and voltage are related by Ohm s law eresistance is dissipation of heat eresistors have polarity Meaningful knowledge Observation 3 From prior labs and interview evoltage is additive across resistors in series eresistance restricts the flow of current From other sources evoltage drives current enegative voltage causes negative current ecurrent changes linearly with voltage eshorts in circuit affect voltage and current Knowledge Final interview evoltage is constant in a Circuit ebattery is the source of voltage voltage affects b
16. b in that circuit Would that make the bulb dimmer AM Yeah So does that help you explain it AM All right So you have the whole total over the whole thing Obviously if took out this resistor R1 that would be bright put that one in and it s dim but this one is dim because it has to divide through the whole circuit whatever power s going through it So does it make a difference what order the elements are in AM would think so but maybe not thinks for a while From this I m thinking no AM initial interview Furthermore though AM s understanding of what resistance is didn t change his practical understanding of what resistance does did change as he was able to correctly predict that a bulb would dim regardless of which side of the bulb the resistance was increased Concepts held by these two students are summarized in Table 1 Bledsoe Electrical engineering students concepts and reasoning Concepts AM initial AM final MJ initial MJ final Current is material or quasi material X X X Current is energy Voltage is a measure of current Voltage is pressure or push Resistance Resistance is the holding back of current Resistance is the restriction of current Table 1 Summary of categories of knowledge held by the two case study students at the initial and final interviews 2 What relationship exists between a student s prior conceptual understanding of electri
17. bservation From interview None of AM s statements in lab overtly contained knowledge from the initial interview From other sources evoltage comes from the batteries evoltage is equal across parallel resistors resistance is the dissipation of power resistance creates heat ewires have negligible resistance resistance is additive when resistors are in series current is measured across resistors Knowledge Final interview voltage is a measure of current battery is a source of voltage voltage is caused by resistance ebulbs have resistance ebulbs convert electrical energy into light energy current takes the path of least resistance current is the flow of electrons ecurrent is energy ecurrent is used up by or shared by circuit elements eresistance holds back current Table 2 Summary of AM s knowledge about the target electrical concepts circuits voltage current resistance across the term Bledsoe Electrical engineering students concepts and reasoning At the end of the term AM expressed frustration with the class He felt that he had been able to take schematics and build circuits from them but understanding the underlying concepts proved difficult AM was unsure why he needed a conceptual understanding of voltage and other concepts if he could build circuits without them He also found the mathematics and digital logic used in class daunting AM mean in lab there wasn t everything kind of mad
18. cal circuits and the student s reasoning processes while solving problems involving circuits 3 How does a student s meaningful learning change as the student grapples with a series of complex problems To observe changes in student knowledge during problem solving and to observe how students used their knowledge as they reasoned their way through problems students were observed and videorecorded during their labs The first lab which was not observed consisted of assembling the base of the TekBot Subsequent labs involved small projects in which students applied concepts learned in lecture During the final lab sessions students designed and assembled the circuitry for their oump bot Conversations between the students and their lab partners and conversations that the researcher engaged them in helped reveal the knowledge that the students were actually applying to the problems in lab their body of meaningful Knowledge The researcher used the subject comments and actions to create a set of statements that summarized the subjects expressed understanding of electrical concepts The statement list was used to create a concept map for each observed lab depicting the body of knowledge that students applied to each problem and the links students made between concepts Concept maps were also created for the initial and exit interviews This allowed comparisons to be made between the initial knowledge set meaningful Knowledge applied to the
19. ction of current This differs from the first concept in that current is not seen as being physically held back but that its flow is somehow restricted in its flow In the water model analogy offered in class resistors were compared with a narrow bit of hose which causes an increase in pressure of the water flowing through Students using this model thought that resistance should slow down the current 3 Resistance is the dissipation of energy While students using other descriptions sometimes spoke of energy dissipation only one student not described at length in this paper used dissipation of energy as his primary means of describing resistance AM began and ended the term with the idea that resistance involves holding back or blocking current Interestingly this concept was challenged in the initial interview when AM observed the results of changing the resistance on either side of a bulb and AM was able to offer a different explanation I Yeah So why does it get dimmer when you put the larger resistor in What is the resistor doing AM It s holding back some of the electricity I Okay And then when you increase the other one what happens AM Gets dimmer Okay Why is that AM Maybe because it figured the current is set quietly back and forth unhooks wires and tries the two resistors for R2 again comparing resulting brightness of the bulb What if instead of a resistor that was another light bul
20. e sense where everything was supposed to go You know could trace where everything was flowing from and to on the board or whatnot was able to set up the protoboards just fine I think that is true for a lot of people They can follow the schematic and follow the diagrams AM But what was actually going on shakes head I Yeah It s another world And trying to match the two becomes and that s part of what I m trying to find out what the instructor wants to Know too is how much of the conceptual piece comes across from what you do in lab Is it all coming together or is it two different worlds A Pretty much two completely different things AM s score on the post survey administered on the last day of class was 15 out of a possible 24 MJ like AM entered the class with little prior knowledge and even less prior experience with electronics MJ however had high math ability and demonstrated a meticulous attention to details both of which she employed to advance rapidly in the class She was very open and vocal about her ideas during interviews and labs providing excellent data for concept mapping MJ had not taken ECE 111 the introductory course taught in the fall because an advisor had steered her into a different class Highly aware that she was behind her peers MJ obtained the materials for constructing a circuit board that had been a lab task in ECE 111 and assembled it herself at home and during lab Vo
21. ed for but is not spontaneously applied applied to the spontaneously tasks Meaningful learning spontaneously Problem Complex applied to other solving problem tasks skills space Inert learning can be recalled when asked for but is not applied to other tasks Interpretation of the purpose of the lab Habits of mind Figure 2 A proposed model of learning within task based curricula based on Whitehead 1929 and Bransford et al 1993 Bledsoe Electrical engineering students concepts and reasoning Both Whitehead s and Bransford s arguments are incorporated into the model in Figure 2 which served as a hypothetical model guiding this study This model proposes that meaningful Knowledge may be discerned in two instances First when students enter a problem space they bring with them a complex array of prior knowledge some of it scientifically accurate and some of it not Those with strong prior knowledge are often more successful at problem solving Anderson 1987 Second students may learn new knowledge in a class setting before approaching a task depending on how the curriculum is arranged Other factors besides enter the complex problem space Students bring with them idiosyncratic interpretations of the purpose of the task Osborne amp Freyberg 1985 a wide range of reasoning skills attitudes toward the task and the subject and habits of mind including study skills and stude
22. ent has to go up So we increased Bledsoe Electrical engineering students concepts and reasoning the resistance and the current went down so now there s a dimmer light bulb Mu final interview explaining the effects of resistors on either side of a bulb Primary concept the nature of voltage While students had an intuitive sense of current as something that flowed like water voltage was a far more elusive concept Lecture notes described voltage as an electromotive force that pushes electrons through a substance The notes again used a water flow model using differences in pressure at two ends of a narrow bit of hose as an analogy for differences in electrical potential on either side of a resistor Several phenomenographic categories of knowledge emerged from student responses 1 No concept of voltage While both students described in this paper had initial concepts around voltage two others interviewed simply had no idea of what voltage was in the initial interviews 2 Voltage is current or is like current In spite of the lecture instructor describing examples of this misconception in class several students described voltage in current like terms such as describing voltage flowing through a circuit 3 Voltage is a measure of current Through instruction students learned that voltage is not current but some students still struggled to understand exactly what voltage was Students used multimeters in class to measure current
23. ever the phrase from the notes that students appeared to assimilate the most was a resistor is a component that purposefully impedes or opposes the flow of electrons This definition was used during the lecture indicating a target concept of impeding the flow of current All subjects were familiar with the phrase the path of least resistance and used it on an interview problem involving two bulbs wired in series with a switch bypassing one of the bulbs Subjects correctly predicted that the bypassed bulb would dim or go out when the switch was pressed because the switch had less resistance than the bypassed bulb However not all subjects predicted that the second bulb would get brighter at the same time that the bypassed bulb went out indicating limitations to their Knowledge of the effects of resistance on the circuit as a whole Bledsoe Electrical engineering students concepts and reasoning Three phenomenographic categories of knowledge emerged 1 Resistance is holding back of current This view often accompanied a material view of current The resistor was viewed as an impediment like a traffic cop holding back traffic or a dam in a stream holding back water One student not described at length in this paper believed that a bulb behind a resistor should get brighter if the resistance was increased because more current would pool behind the resistor making more available to the bulb 2 Resistance is the restri
24. iscussions around these concepts were more situational than theoretical less about what voltage and current were than Bledsoe Electrical engineering students concepts and reasoning what they were doing at the moment Nevertheless her expectations about the basic concepts did in some cases influence her approach to the activities For example her concepts of directional current flow influenced her to always check that she was installing resistors and other components in the right direction At the final interview MJ s knowledge of electrical concepts had developed as had the number of connections she made between concepts Figure 9 determines Bulb brightness Voltage is constant of Sa source of affects may circuit be elements used Current m o which make up a may be takes path restricts conserved of least K ina lt lt is additive across a Battery Resistance which is divisible Figure 9 Concept map of MJ exit interview Her concept of voltage had moved from voltage as pressure to voltage as that which drives current a slight but important difference in that the connection between voltage and current was more clear She also saw a clear relationship between resistance and voltage recognizing that higher resistance was associated with higher voltage MJ still had strong expectations about the directional nature of current and had not quite let go of an image of current as some
25. lab problems and the knowledge set that emerged at the end AM was observed during three lab sessions In two of the labs AM spent a good deal of time assembling parts of the TekBot according to written instructions and the conversations did not reveal adequate data During the second observation however AM carried out a conversation with his lab partner that yielded a number of statements about the target concepts Bledsoe Electrical engineering students concepts and reasoning reaction light by has is like with takes path W Resistance terial of least materia ba holds back p rE is used up by comes from circuit 2 mery elements chee i oe are used up by come from electrons lt CE gt winen er divisible Figure 4 Concept map for AM initial interview which make up a Figure 4 illustrates AM s concepts during the initial interview and reflects the limited knowledge that AM held when he came into the class Expressed concepts and the connections between them are fewer than what emerged in the final interview which one would reasonably expect As can be seen in the figure AM s concept of voltage was not only relatively undeveloped it was also connected to only one other concept that of current It is not unusual for students with low knowledge of electricity to be more familiar with current than with voltage Most of his discussion involved describing current which he understood to the the flow
26. ltage is like _ pressure determines Te brightness of pee source of creates Bulb light by p ener conversion gy Battery of A is circuit a is used ithe electr ns elements up by XK gt which make up a takes path restricts of least Resistance i 7 z creates a lt ______ XN which is divisible Figure 7 Concept map for MJ initial interview Bledsoe Electrical engineering students concepts and reasoning A concept map for Mu s initial interview Figure 7 shows some initial development of concepts as well as some alternative conceptions In this interview MJ was unsure of exactly what voltage was She had learned in class that it was something like pressure She noted that voltage affected bulb brightness and that it was supplied by the battery She had not yet made a connection between voltage and current which was not unusual for other students entering the class Hence her map shows a cluster of concepts around voltage and another around current with little that links the two Like many students MJ initially expected current to be used up by circuit elements such that the first bulb in a series would be brighter than a second By the time she reached the interview however she had assimilated some of the lecture material and was beginning to think in terms of voltage around the bulbs She thought of current as something that flowed directionally a concept that remained strong with her th
27. mount of what don t know Voltage or current Um so they re going to equal the same And but this one A and B has to divide it because they re in parallel so both of them are a lot dimmer than that C AM final interview MJ began the term with a material view of current and struggled at the beginning of the term with the ideas that current is shown flowing one direction while electrons flow in the opposite direction For a student with a material view of current this apparent conflict makes no sense MJ That s something that I m kind of confused think the electrons are going from negative to positive but the way we always draw it is you know the current is always flowing from positive to er mean it s going into the positive direction so pauses l m not really sure think it goes like this moving hand clockwise So what is it that actually goes MJ Electrons I Okay and they go MJ That s the current Mu initial interview The only way that MJ could reconcile the two conflicting ideas was to let go of her views of flowing electrons and view current in terms if its mathematical relationships with voltage and resistance It s changing the current because the current through all three of them has to be the same because they re all in series but the current let s see since V IR if you increase the resistance then the current has to go down And if you decrease the resistance the curr
28. nd the basic concepts At the end of the term students filled out the electrical concepts survey a second time and were interviewed to develop a description of their electrical concepts at the end of the term using the same protocols as the first interview At this time copies of students lab reports were also collected Interviews and videotapes from labs were transcribed and analyzed using a phenomenographic perspective using the analytical methods described in Ebenezer amp Fraser 2001 Descriptions of mutually exclusive categories of knowledge were developed from student responses and matrices developed to track whether student conceptions changed during the term Individual student responses were used to develop a series of Bledsoe Electrical engineering students concepts and reasoning concept maps which were analyzed to examine both changes in student knowledge and how students used that Knowledge during the reasoning process Reasoning was described according to a cognitive model of reasoning by way of mental modeling derived from Nersissian 1998 This view arises from psychological literature on semantic reasoning which plays a larger role in human reasoning than the traditional inductive deductive models allow Craik 1943 Vandierendonck and de Vooght 1996 also argue that humans tend to solve problems including simple logic problems by constructing mental models in memory rather than using classical rules of argument
29. nt self efficacy The complex learning space is itself a learning environment in which students not only apply Knowledge but construct new knowledge Emerging from this space is the student s knowledge now transformed Some of the resulting knowledge will be meaningful that is students will soontaneously apply it to further tasks Some will be inert the student will be able to recall the Knowledge if asked but will not think to use it on a related task The model therefore describes an iterative process Each time a student enters a task based environment the student brings the knowledge from prior learning some of which will be applied to the new task Method This paper reports on a portion of data collected during a larger study to be described in Bledsoe 2007 in which students with high prior knowledge and students with low prior knowledge as determined by a survey of electrical concepts were interviewed and observed as they participated in a task based laboratory section of an electrical engineering course This paper will describe two students who entered the course with low prior Knowledge how the concepts held by these students changed the reasoning displayed by these students and their self perceived success in the course These two students were of particular interest because of their differing degrees of success in the course The subjects of this study were selected from first year engineering students enrolled in ECE 112
30. o phenomenographic categories emerged 1 Current is material or quasi material This view was accompanied by the belief that current could be used up like a fuel by circuit elements or could even be dammed up behind resistors The analogies used in lecture in which current was compared to water flowing in pipes may have reinforced this view 2 Current is energy Subjects holding this view often defined current as the flow of electrons but when describing current in an actual circuit tended to use energy related terms involving the use or dissipation of energy power or electricity AM s initial conception of current was highly material In explaining how the light bulb in the circuit board lit up AM described light as being caused by a chemical reaction between power and chemicals in the bulb I Okay so inside the bulb itself what s happening AM The power s mixing with whatever s inside um the turns to the chemical that s inside it I Okay And when you say power what do you mean when you say power AM Electron flow AM initial interview By the end of the term AM s views of current still contained material elements He talked less about current and more about voltage in the final interview but did not distinguish clearly between the two concepts AM Um well say if this was like one light bulb pointing to A and B It would have to equal the same amount as coming into this one pointing to C A
31. ors it was surprising that Bledsoe Electrical engineering students concepts and reasoning this did not come out in the interview He did however understand that a single resistor affects the entire circuit not just those components that are downstream energy conversion creates i A is caused by isa a source of isa measure of y Battery takes path W Resistance of least i holds back ren is emia is additive in used up by shared by circuit which make I ESE elements upa C Circuit which is gt divisible Figure 6 Concept Map for AM exit interview In Table 2 the body of AM s meaningful knowledge is summarized across the interviews and observations Because the interview situations involved asking students for their understanding of particular terms the knowledge gained in that situation encompassed both meaningful knowledge spontaneously used and inert knowledge that which was recalled when asked for Knowledge that was expressed and used in lab spontaneously is listed here under meaningful knowledge for the lab observation Knowledge Initial interview evoltage is like current current is a material that is used up by circuit elements ecurrent is electrons which come from the battery eresistance holds back current current takes the path of least resistance light in a bulb is created by a reaction of chemicals with current Meaningful knowledge Lab 2 o
32. roughout the term and that seemed to contribute to her puzzlement over the apparent conflict between current flow and electron flow So long as she thought of both current and electrons in quasi material terms it did not seem logical to her that the two should flow in opposite directions MJ was observed during four labs three of which yielded sufficient data to construct concept maps Her map for Lab 2 is presented here Figure 8 for comparison with AM s concept map for the same lab Battery loses charge 7 7 polarity as it i have which make up a pa is resistors additive across circuit j elements caused by determined by reversed gives related by I ae in excess Ohm s Law reading overheats to related b eae Ohm s Law gt C Current to dissipation of heat Figure 8 Concept map for MJ Lab 2 Because the lab involved touching the resistors to see if they were hot or not MJ expressed strong awareness of resistance as involving the dissipation of heat She knew that too much current could cause something to overheat again expressing the strong awareness of the cautions delivered in lecture about smoking their resistors MJ approached much of the lab mathematically She was adept at using Ohm s law to calculate resistance voltage and current using measurements taken in class The batteries she discussed very little except to mention that the voltage decreases with the charge Like other subjects her d
33. rvey was 8 out of 24 However she had an aptitude for math and had been counseled by an advisor to try electronics as a major The highest math class that MJ had taken was MTH 256 Applied Differential Equations Question 1 What phenomenographic categories of common knowledge regarding direct current electrical circuits are constructed by first year electrical engineering students Transcriptions of surveys and conceptual interviews at the beginning and end of the term were examined and coded for instances of student statements regarding current voltage and resistance Codes were sorted and merged to form a hierarchical set of phenomenographic categories of knowledge which were used to describe student concept development over the course of the term Primary concept the nature of current Lecture notes provided for the class explicitly stated that current consists of electrons in motion through material The phrase current consists of moving electrons was printed in bold face at the top of the class Bledsoe Electrical engineering students concepts and reasoning notes for the first day of class How students interpreted and used this phrase may have depended on their understanding of what electrons are Students who viewed them as solid particles tended to have a material view of current while students who thought less about moving electrons and more about the effects of current tended to view current in more energetic terms Thus tw
34. stant in lab to understand the difference What is interesting is that little of the knowledge that AM demonstrated in the initial interview were expressed in this lab This may have been because AM was unsure of so many concepts and that concepts taught in lecture had more direct value to him than the concepts he initially held Further AM s focus was on using the concepts rather than defining them hence most of the links between concepts relate to the observed effects of voltage resistance and current on the circuits he built A few of his initial concepts however appear related to the connections he made between concepts in the lab His essentially material view of electricity as the flow of electrons and the idea that current flows in a particular direction was reinforced by his discovery that circuit elements have polarity and that a reversal of current causes a negative reading on a multimeter when there should be a positive reading and vice versa The exit interview Figure 6 shows more developed concepts of voltage and resistance though the number of connections between concepts remained about the same AM believed that voltage was a measure of current but he knew that batteries were a source of voltage and that voltage is related to resistance so though he was unclear about what voltage was he had better understandings about what it did Given that he had spent a large part of one lab measuring the dissipation of power from resist
35. sure on a circuit that they had built then the circuit might be incomplete hence voltage is only detectable in complete circuits where presumably current is flowing Bledsoe Electrical engineering students concepts and reasoning circuit resistors if incomplete elements has no 4 installed backward is equal create negative across is parallel measured i are Voltage across is additive in a series of heat N is a creates Current z source of Resistance negligible wires Battery in is positive SS during is disspation k dissipation of of isa l wena eee power Figure 5 Concept map for AM Lab 2 AM was aware that the polarity of certain circuit elements could affect the measure of voltage if they were installed incorrectly and discovered that installing a diode backwards caused it to heat up to the point of smoking Dissipation of energy was also noted in a lab activity in which AM and his partner installed the resistors into a protoboard in both parallel and series formations and measured voltage and current AM was able to apply knowledge from lecture as he predicted that voltage should be equal across parallel resistors AM s attempts to measure voltage and current however were hampered by his difficulty in distinguishing between measuring voltage across a resistor and current through a resistor He persisted in attempting to measure current across the resistor and required repeated instruction from the teaching assi
36. sychology s response Washington D C American Psychological Association Breton G 1999 Some empirical evidence on the superiority of the problem based learning PBL method Accounting Education 8 1 1 12 Chi M T H Bassok M Lewis M W Reimann P amp Glaser R 1989 Self explanations How students study and use examples in learning to solve problems Cognitive Science 13 145 182 Chi M T H 1992 Conceptual change within and across ontological categories Examples from learning and discovery in science In Giere R N ed Cognitive Models of Science Minnesota studies in the philosophy of science pp 129 186 Minneapolis University of Minnesota Press Craik K 1943 The Nature of Explanation Cambridge MA Cambridge University Press 20 Bledsoe Electrical engineering students concepts and reasoning diSessa A A 1982 Unlearning Aristotelian physics A study of knowledge based learning Cognitive Science 6 37 75 Ebenezer J V amp Fraser D M 2001 First year chemical engineering students conceptions of energy in solution processes Phenomenographic categories for common knowledge construction Science Education 85 509 535 Enarson C amp Cariaga Lo L 2001 Influence of curriculum type on student performance in the United States Medical Licensing Examination Step 1 and Step 2 exams Problem based learning vs lecture based curriculum Medical Education 35 1050 1055
37. t brings to a task consists of prior Knowledge held before instruction and any direct instruction just prior to the task What emerges is two sets of Knowledge meaningful knowledge that the individual values and uses spontaneously in the task and similar tasks and inert Knowledge that may be recalled if asked for such as on an exam but is not used spontaneously Hence inert and meaningful knowledge are related to both retention and transfer of knowledge Figure 1 illustrates Whitehead s model Bransford et al 1993 in discussing Whitehead s propositions argued that task based instruction is more likely than didactic instruction to result in the development of meaningful knowledge Bransford proposed that meaningful learning applied to tasks is retained and is likely to be transferred to further tasks Bledsoe Electrical engineering students concepts and reasoning Prior z knowledge instruction Student a knowledge brought to the task Inert learning Meaningful can be recalled when learning asked for but is not spontaneously applied applied to the spontaneously tasks Figure 1 A diagram of learning based on Whitehead s 1929 concept of inert and meaningful learning Prior knowledge Direct strong weak instruction Student eon knowledge brought to the task Inert learning Meaningful can be recalled when learning ask
38. thing quasi material that is used up by the elements in a circuit as seen by her predictions that the first bulb in a series should be dimmer than the second though she stated explicitly that both current and voltage were conserved in a circuit Table 3 summarizes Mu s changing knowledge and meaningful knowledge across the term This table includes all three observations that yielded sufficient data MJ expressed much higher confidence near the end of the term than AM did about her performance in class and in lab though her confidence was always somewhat tentative MJ knew she began the class behind her peers in knowledge and strove to bring her knowledge up to what she considered the necessary level During lab she frequently asked the teaching assistants for help or for confirmation of her ideas and often would have the TAs check her circuits or her diagrams of her planned circuits before proceeding In the first labs she often asked the TAs about the functions of the various parts of her TekBot Because of her high math ability she was less daunted than others by the mathematics and logic presented in class Her score on the post survey presented on the last day of class was 16 out of a possible 24 Bledsoe Electrical engineering students concepts and reasoning Knowledge Initial Meaningful interview knowledge Observation 1 From interview voltage is pressure ebattery supplies voltage evoltage is like pressure voltage
39. tus New York Springer Publishing Company Shipstone D 1985 Electricity in simple circuits In Driver R Guesne E amp Tiberghien A eds Children s Ideas in Science Miltone Keynes Open University Press pp 33 51 Vandierendonck A amp de Vooght G 1996 Evidence for mental model based reasoning A comparison of reasoning with time and space concepts Thinking and Reasoning 2 4 249 272 Vernon D T A amp Blake R L 1993 Does problem based learning work A meta analysis of evaluative research Academic Medicine 68 7 550 563 Whitehead A N 1929 The aims of education amp other essays New York MacMillan 21
40. ulb brightness voltage drives current ecurrent may be used up or conserved in a circuit eresistance restricts current eresistance is additive in a series circuit eresistance affects voltage Table 3 Summary of MJ s knowledge about the target electrical concepts circuits voltage current resistance across A Tentatively Revised Model the term As Whitehead 1929 described these two students entered the class with a body of prior knowledge and continued to acquire knowledge during the lecture portion of the course Some of that knowledge expressed initially and some of the knowledge that was delivered in the lecture emerged in discussions during lab as the students worked to solve the problems presented In MJ s case the researcher was able to see what knowledge became meaningful from one lab to the next However bodies of meaningful and inert knowledge do not remain static Both students were learning new knowledge in lecture and their knowledge changed during lab as they worked through problems and observed the effects of voltage current and resistance on various circuits What knowledge emerged as meaningful changed as the context of each lab changed Meaningful knowledge appeared to be highly situational and tied not only to the problems presented in the lab but to the students interpretation of those problems Bledsoe Electrical engineering students concepts and reasoning
41. we re measuring electrons with them AM Uh no thinks Hm The current would be the flow of electrons and R resistance is how many electrons are being held back er not how many it s just just a number mean 4 7 ohms it s not going to hold back 4 7 electrons So yeah guess it makes sense that voltage would be the number of electrons AM initial interview Bledsoe Electrical engineering students concepts and reasoning By the end of the term AM realized that voltage was not current and moved to a conception of voltage as a measure of current I Or when you were measuring voltage in lab What was it that you felt you were measuring AM I m going to say it s the change of um like electrons flowing Not flowing Just the like either the drop or the increase between one point and the other AM final interview Early in the term MJ was forming models of voltage as a source of pressure to move current I Yeah basically what is it that that the meter s actually measuring What is it that those numbers mean M Well its not measuring the current it s measuring the pressure of the current The um way he explained it in class was relating it to water where the quantity of the water is the current and then the pressure of the water is the voltage you know the pressure of the current Mu first observation In the final interview MJ had moved to talking about voltage as potential energy when asked
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