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Science Learning Centres

09018 and 09039 SASP Final Assessment Feedback Sheet

Candidate Number: Physics B Tutor: Title of Task:

Comments Linked to Criteria

Understanding of key ideas:Section A: You demonstrate a clear grasp of science education research relevant to this topic, commendably aiming to identify and remove misconceptions through active learning, including original activities such as a mock episode of the BBC quiz show QI. As you freely admit, you are not yet able to teach capacitors at A2 level confidently (e.g. describing the time constant RC as being ‘complicated’) but you are working towards this goal.Section B: Reflections on your learning journey are thoughtful and extensive, implicitly but not explicitly drawing on a learning journal kept throughout the course. As well as your own learning, you describe its positive impact within your department.

Use of material:In both Sections of the assignment, you draw appropriately on relevant literature and critically link it to your own experience in the classroom, presenting a well-constructed discussion which enables you to identify specific improvements. In Section A you are able to be critical of some questions included in your student questionnaire. In Section B you make clear how thinking deeply about both student perceptions and also particular topics has improved your general approach to teaching physics.

Range and comprehension of sources:Your choice of primary and secondary sources is balanced and comprehensive, demonstrating your research initiative. The use of diagnostic questions, before and after teaching, together with and end test and colleague observations together provide useful insights into student learning.

Communication:Both sections of the assignment are well-structured and use appropriate specialist language. The use of a table in Section A very effectively conveys the information necessary to a proper evaluation of the teaching scheme and implications of your students’ difficulties.

Level of citation:You have used the correct convention for References. Some citations are too general (should mention specific pages).

General Comments:The assignment as a whole demonstrates the considerable progress that you made during the course, in both subject knowledge and teaching approaches. One statement indicative of your improved confidence stands out: ‘I can now think about things more calmly and work things out rather than panicking and guessing.’

Grade awarded: 65Classification: II(i)

SASP Final Assessment

Section ATopic: Capacitance (Year 13)

I have chosen to look at the topic of capacitance. I have not had to teach the challenging concept of exponential change before, and have always found the teaching of electrical concepts difficult – and those of the department, which does not currently have a scheme of work in place for Year 13. Due to the limited lesson time I had with the students as they were behind in their progress through the course, I did not teach the lessons exactly as they appear here (Appendix A). Instead I chose specific activities and taught a pared down version, over 4 lessons. I was fortunate in that the students were covering nuclear decay with their other teacher a few lessons ahead of my timetabled lessons. He was therefore covering the concept of exponential changes with them, which freed up some time for me to be able to look at the misconceptions in basic ideas of electricity before I moved on to the higher level work. I had several discussions with him at school regarding the teaching of exponential changes, and he was able to trial one of my activities with the class and provide feedback.

Progression from KS3 and KS4The topic of capacitance relies on students having a solid understanding of electrical circuits and the concepts of current, charge, potential difference and electrical energy. At Key Stage Three they first meet electricity in unit 7J (Electrical circuits). They need to build on the ideas developed at Key Stage Two (unit 4F 'Circuits and conductors' and unit 6G 'Changing circuits') where they look at conductors and insulators and simple circuit ideas, such as the need for a complete loop for a circuit to work. Students often start with a sequential view of what is happening in a circuit, as it is common for people to think of one thing causing another to occur. However this can cause problems in electricity studies as students often think of effects only occurring ‘downstream’ in the circuit, not realising that a change in one area will affect the whole circuit (Driver et al 2008 p122). This misconception will cause them to find it difficult to use models and ideas of current and energy to explain what is going on in a circuit, which they need to do in unit 7J. Therefore you can see how a simple issue early on can arrest a student’s progress further down the line.By the end of unit 7J they should have an understanding of what current, voltage and resistance are, and be able to measure current. Common misconceptions that I have found here are confusions between the ideas of current and energy in a circuit, leading to the idea that current is used up around the circuit. This idea in

particular seems to be very difficult to supercede despite additional teaching – students seem to pick this idea up early on during primary school, and be reluctant to discard it, even though it conflicts with the accepted ideas relating to series and parallel circuits that they will now have to deal with (Shipstone, 1993). Often students end up with two ideas of what is going on - one based on their pre-existing thoughts and experience, and one they have learnt in science (Hartel 1982). It is not surprising therefore that the scientific one is the one most quickly forgotten. Students also in my experience find it difficult to define voltage, current, resistance and energy, and often use the words interchangeably. It has been suggested that as most students meet the concept of current before voltage, that they have no concept of voltage, and often assume that it is current (Driver et al 2008 p122). The term ‘power’ is also bandied around without any clear understanding of what it means in this context. Electricity is touched on again in year eight with unit 8J 'Magnets and electromagnets' and again in year nine with unit 9I 'Energy and electricity'. Only unit 9I is of relevance to this assessment, as it introduces ideas of measuring voltage within the circuit, and being able to link voltage to the energy transfer occurring. It also suggests the use of the term potential difference for some students for the first time, and with it the idea that potential difference makes current flow.At Key Stage Four in the AQA syllabus these ideas are explored again. Although much of the content is the same, there are additional ideas to help the students explore the concepts in more depth, such as the ideas that electrons are carrying the electricity in the wires. The other major difference is the expectation that students can look at the mathematical relationships between the various factors, and so explore their relationships quantitatively as well as qualitatively.It is not until year twelve that the concept of charge is explored mathematically and students learn to think of electricity as a flow of either negative or positive charges rather than a flow of electrons. Potential difference is re-explained as the energy transferred to components per unit charge, distinguishing this from the new term ‘electromotive force’, the energy supplied per unit charge. Concepts are re-visited but in more depth to allow students to understand the concepts to the extent of being able to effectively design their own circuits. Terminology remains of the utmost importance and therefore fixed misconceptions of these from lower down the school can be a barrier to further progress and understanding. New components such as semi-conductor diodes are introduced and their patterns of behaviour explored. Material properties such as resistivity are shown to be distinct from factors associated with particular components (such as resistance). Although there is much here that is complex, the fundamentals are thoroughly revisited. When I was teaching this section to my class last year, I found myself teaching virtually the same content to

them that I had taught to the year elevens the period before. What I hadn’t noticed before I did this SASP course was that the assumption in the text books and in my teaching was that basic terminology was already understood. In fact with hindsight it would have been better to concentrate more on that than re-covering the patterns of behaviour of various factors within circuits, as these were more readily recalled. In year thirteen the idea of electrical fields comparative to magnetic fields is introduced, and this then leads into the work on capacitors. Students had therefore already come across such things as the idea of the mathematical relationship between electric field strength, potential difference and the distance between two charged plates expressed by the equation E = V/d. In addition, those of the students following the maths syllabus (all of those in this class) would have also already covered both integration and differentiation at this point, and have some notion of natural logs and the exponential function from their maths lessons, which would be of use to cover the charging and discharging of capacitors.What I find most disturbing about these misconceptions is that they are so beguiling to students. People will believe what they think is correct even if it doesn’t fit in with the other evidence often because they simply don’t think about it deeply enough. It has been suggested that the reason students fail to conceptualise electrical circuits properly is because even though they have learnt the meaning of terminology, they fail to connect it to factors associated with circuit itself (Eylon & Ganiel, 1990). My understanding of this topic has changed due to this assignment and it worries me what other gaps in my knowledge there may be. For example it was only when I read an article that highlighted the fact that no-one really knows what charge is that I realised that I also could not define it (Williams, 2007).

Rationale behind the teaching and learning approaches employed I decided to start with a recap of basic electrical terminology to try to identify any misconceptions. Electricity is a key area where students struggle as they find it difficult to visualise what is going on, as many of the factors (for example the movement of electrons, or the potential difference) cannot actually be seen. Although we have various models we can use to help them grasp the concepts, all models do have flaws. The idea is to simplify the information enough so that it can be understood and used as a guide to understanding the new concepts, but not so simple that it is going to become obsolete as more knowledge about the system is unearthed (Taber et al, 2006). The incomplete nature of the analogies can lead to increased misconceptions (Ashmann, 2009). Once you get to A level it is important that students are aware of both the value and limitations of these models so that they can get

the most benefit from them, and so I tried to put this into the questionnaire. The advantage of working with sixth formers is that they have sufficient general knowledge to be able to understand the ideas behind the possible analogies in a way that younger students may struggle with (Driver et al 2008, p123).I also chose to start with a questionnaire as this would enable me to get an idea of different student ideas on the topic, as it is clear that in order to teach students more effectively it is a good idea to take into account their existing views (Driver et al, 1993) and use these to help you plan the way in which you approach a new topic. I used various sources to identify possible areas of weakness (see Appendix A) and used these to make up the questions. I decided to let the students sit in their working groups and allow them to discuss any issues that arose from the task, whilst I listened and made notes on what they said. In this way I could identify from their discussions areas which would require some additional work. It has been noted in some research (Michael Watts & Gilbert, 1983) that the usual necessary brevity of student-teacher interaction can lead to students being able to use a few pieces of terminology correctly and in this way convince a teacher that they have understood what is going on, so the teacher moves onto the next concept, unaware of the problem. By asking them to discuss their ideas I would have a better idea of the level of their knowledge.Once we had completed the questionnaire activity, I gave students some questions to think about that were taken from an episode of QI, the BBC quiz show. The students had seen the programme before and were both interested by the connection and keen to watch the episode. The activity required them to answer the question as interestingly as possible, as on the show itself, but I also asked the students if they could come up with the wrong answers that the quizmaster was expecting the panellists to supply. This also created a very worthwhile discussion about possible misconceptions, following on from which we watched the relevant sections of the programme. From these general beginnings in the first lesson we moved onto the idea of what a capacitor was and some its uses in lesson two, using practical ideas from discussion with other physics members of staff and various texts (Jerram, 1999; Ehrlich, 1990; Solomon, 2000). The idea was to start with practical work to illustrate a point, so that students could explore the ideas for themselves, then to move to explaining how it works, before any mathematical work was introduced. There are many studies that suggest that this approach leads to a fuller understanding of the underlying concepts (Taber, 2009) and a greater confidence with the subject as a whole. Lesson three then looked at the energy stored in a capacitor, followed by a lesson looking at the total capacitance of capacitors in series and parallel. Lesson five looked at the concepts involved with the idea of exponential changes, with lesson six applying this information to the charging and discharging of capacitors. Lesson seven moved

onto looking at the complicated concept of the time constant and finally lesson eight was a concluding lesson which looked at how well students had understood the topic. Taught in this way much of the maths involved in the first half of the scheme is simple arithmetic and basic algebra, leaving till later the more difficult concept of exponential change.

In all the lessons, I tried to offer a range of tasks, focusing on student led activities. I hoped that if the students were able to discuss things together with a few pointers from myself, then they were more likely to retain the knowledge in a way that would be useful to them. Much of the research I looked at for all the SASP assignments has emphasised the need to allow students to talk amongst themselves in order to try to reorganise the new information they had assimilated during the lesson with their existing ideas (Engel Clough & Driver, 1985; Michael Watts & Gilbert, 1983). When choosing practical activities I did try to act upon ideas gleaned from education research and use my knowledge of students’ misconceptions to design experiments that would contradict these ideas and cause the students to reconsider their thoughts (Driver et al, 1993; Shipstone, 1993). However of course as capacitors are not, in general, something that students have come across before (and therefore have no preconceptions about), this was not easy. Instead I had to ensure that the experiments and other activities reinforced the underlying terminology. I also tried to emphasise the different concepts of charge, current, potential difference and energy as separate, as often students can think in terms of one measure of electricity only, as it takes time to develop complex ideas. It takes time for us to assimilate and embrace any conceptual changes we make, and problem is that during that time it is possible for us to reinforce incorrect ideas as we interpret new data in terms of what we already know ((Driver et al, 19932). This can help to explain how year thirteen students who have studied the concepts involved in electrical circuits several times can still carry forward basic misunderstandings. I decided to use activities that involved peer marking so as to avoid the possibility that I could unconsciously encourage students towards what I want them to say. This so called ‘right answer syndrome’ (Driver et al, 19932) can lead to students (and staff) getting the answer correct but in a superficial way, so that any underlying issues around the subject are ignored and therefore not resolved. With the students doing much of the interpreting and evaluation themselves, I can reduce the impact I have on this area. In the same way I tried to ensure that any conversations I had with students in class allow students to work out the ideas for themselves. One interesting study suggested the advantages of fast feedback to encourage progress and group discussion (Emmett et al, 2009). I used one of their ideas, that of asking students to sketch and

interpret graphs when looking at how current, potential difference and charge varied with time.

Evaluating effectiveness

In order to evaluate the teaching and learning that went on I used several methods. I gave students a questionnaire based on potential misconceptions and knowledge I was hoping to reinforce or introduce, which was linked directly to some of the learning outcomes of the unit. In addition I gave students an exam style set of questions at the end of the section. It was apparent from the results of the introductory activities that information learnt early on in schooling is surprisingly resilient to change. Despite these intelligent students meeting certain terminology repeatedly over the course of their education, several had carried through misconceptions from the start, and others used terminology incorrectly in conversations even though they knew the correct usage. Here follows a brief analysis of the answers to the questionnaire. The values in normal type show the first attempt at the questionnaire, whilst those in bold indicate the second attempt:

Confidence scale:Qu. #

Basic topic area

Correct answer

Sure I’m right

Fairly confid-ent

Not very confid-ent

Just guess-ing

1 Recap of values and units

100%100%

50%100%

50%

2 Definitions 13%88%

50%63%

50%37%

3 Definition 100%100%

25%75%

50%25%

25%

4 Exponential relationship

75%100%

50%100%

38% 12%

5 Exponential relationship

75%100%

50%100%

38% 12%

6 General miscon-ceptions

0%75% 100

%

38% 37% 25%

7 Analogies 13%100%

13%88%

13%12%

24% 50%

8 Exponential

0%38%

38% 50%100%

12%

relationship

9 Capacitors 0%88% 75% 25%

38% 62%

10 Standard form

88%100%

50%75%

50%25%

As a general rule of thumb, the number of students achieving the correct answers and the students’ confidence in their answers increases the second time round, as would be expected. Rather more discouragingly, there is still a significant proportion of students failing to get the correct answers on their second attempt. I was worried that allowing the students to discuss and go through answers during their first attempt may have been unwise as I thought that they would have simply remembered the correct answers, rather than worked them out for themselves. The fact that students still got questions wrong shows that this did not routinely occur; this is demonstrated well in question 6, where students merely had to recall a right or wrong answer, yet still made errors the second time around.Certain questions with hindsight were too general in their wording, or too open ended. It is difficult to properly analyse results when there are many sections to a question (e.g. question 2, if one part was wrong then I marked the whole question wrong) or when a question is interpreted by some students as straightforward and by others as open ended (e.g. question 3). Answers for question 3 (Electricity is…) ranged from the simple (‘energy’) to the increasingly complex (‘induced through moving conductor in magnetic field’) and were often linked to other values (‘the flow of electrons’). These differences could have been due to students’ knowledge but also their enthusiasm – some clearly tried to write out what they knew in full, whereas others went for a quick one word answer in order to be able to move on. However, in general both the complexity and depth of answers increased, and student confidence increased with the second attempt. Personalities also played a part when looking at the confidence levels, as some students have less self confidence generally than others, and are reluctant to ever state that they are sure that they are right about something. I also realised when I listened to their discussions in class that my own ideas of what was correct and what was not were not concrete enough, and on some occasions had to ask for guidance from the other physics teachers present. It has been shown (Gunstone et al, 2009) that it is common for physicists to have issues with the concepts surrounding electricity, and that in fact if a teacher thinks the topic is straightforward, they almost certainly do have misconceptions of their own. The answers given to question 2 were interesting as many of the answers were good text book answers however the students’ actual working knowledge of what the explanations meant were not always

so clear. For example although most students could define potential difference, e.m.f. and current (or at least voltage and current) they still really struggled with part of question 6 (‘voltage can occur independently of current’) which used that information. Students also repeated basic mistakes regularly in class whilst discussing new ideas. Several times students would ask questions that would betray the fact that their knowledge was built upon shaky ground (for example simple ‘Don’t you mean current?’ when I was talking about charge build up on the capacitor plates). This is not surprising really as when pressed for definitions I myself became flustered several times, and on one occasion the students picked up the fact that I had used the wrong term (charge when I in fact meant current) and this of course did not help matters at all. Finally of course is the fact that there are still sections of this topic that are based on slightly unclear intellectual ground, for example the issue of ‘what is charge?’ . It was shown that although students were aware of several different analogies for the electrical model, they were most comfortable with the mechanical ones, in much the same way of other research findings (Driver et al 2008 p122). Several of the other models caused much discussion as students tried to remember how they worked; they were not comfortable with using them and could not see their value. The questionnaire (Question 7) also showed that although many could recall how the models worked, they were less confident at being able to analyse their limitations. Introducing the rope loop model as a physical exercise for the students to explore and attempt to evaluate as a group was more successful in this respect. I could see that how we introduce students to new ideas in the first place is of the utmost importance. By approaching things in what we think is an easy way we may not in fact be helping at all, and some models may indeed reinforce incorrect ideas (Driver et al 2008 p117). I think that in my school we need to look at our Key stage three scheme of work carefully to see if there isn’t a more useful model we could give students to hang their ideas on. For example alternative suggestions to our current model would be to use the idea of looking at voltage first rather than current (Driver et al 2008 p122). This may help prevent students latching on the more intuitive ideas surrounding the definition for current and let them see voltage as a separate value in its own right that is not a property of current (Driver et al 2008 p124). A less radical alternative would be to consciously introduce several different analogies so that each time you change the idea you get through to a few more students (Driver et al 2008 p123) rather than each teacher using the model they think works the best. The traditional approach to physics teaching often involves teaching the facts and allowing students to use mathematical formulas and practical work to prove that the facts are true (Osborne and Dillon, 2010). However, although these are by no means unimportant, it has been suggested that these should remain the ‘endpoints’ that

students work towards, rather than the beginning points’ they start with (Mulhall and Gunstone, 2008). With this in mind, I had allowed time for activities based on the students being able to discuss what is happening. As is suggested in the Mulhall and Gunstone study (2008) I tried to ensure that my input was more ‘asking questions to promote student engagement with ideas, rather than give answers and information’, although this was not easy to do, as I found it quite difficult to form the types of question on the hoof as it were during the lesson. As I was recapping work the students had already covered with their other teacher, I thought that this would be an easy section, and that the maths involved looked much more complex than it actually was. However once I started to go into matters I realised that my views were based upon my existing knowledge of maths, which is of a fair standard, but not good enough to stand up to the repeated questioning of an A level class. In the end I concluded that the lessons were in part successful. It can be seen from the questionnaire results that some of the issues addressed were successfully dealt with. The students also performed well in the end of unit test (average score of all students 63%, average score of the top 7 students, 72%) which linked directly to the learning outcomes of the unit.The questionnaire focussed mainly on these terminology issues of understanding and it can be seen that the lessons met with some, albeit limited success. Although I felt that students’ understanding and confidence with exponential changes improved, this does not translate into dramatically improved results in the questionnaire. This was linked to the way my questionnaire was constructed, and with hindsight I would not have used a simple ‘right/wrong’ system with open ended questions, as this made it difficult to give students who had the main ideas credit for what they wrote. The answer required students to show a certain dexterity with words in order to explain themselves properly, as it is a difficult concept to get across. I often felt that the students knew what they were trying to say, but not how to say it, and therefore the results are more indicative of a fault in the questionnaire than with the progress made. Although most areas of terminology understanding improved, the confidence students showed in this area did not always reflect this to the same extent It is also worth noting that although students did show improvement in their correct use of terminology in the questionnaire, this did not always translate to improved use of that terminology verbally. I found that the misuse of terminology was fairly ingrained to the extent that even bright Year 13 students, some of whom are A and B grade candidates, can still show fundamental flaws, even when they are bright enough to expect that you are including tricky questions. Clearly brushing up on the rudimentary aspects underlying a subject quickly at the start of a topic as I usually try to do is fairly pointless. That is not to say that recapping is not a worthwhile activity but exactly the opposite. It is such a fundamental activity that it is

worth spending more time, as the saying goes you cannot build a good house on poor foundations. In sixth form work the concepts are more difficult and therefore it is more important to ensure that the basics are clearly understood. It should also be remembered that I had already attempted to recap with their class their knowledge of electrical concepts back in Year 12 when they studied Kirchoff’s laws, and although I thought I was successful at the time clearly many of the students still carried forward their previous misconceptions. This also highlighted the unsuitability of this topic (and my perception of it) for this assignment. Electricity itself would have been a good topic, but capacitance did not fit well. I had two main themes to look at, that is misconceptions relating to electricity and the complexity of exponential relationships. In trying to include both I feel that I didn’t fully engage with either, leading to scheme of work that feels incomplete despite being fairly large. Obviously not teaching all the content did not help here, and I will need to look at this again before I can put it into the school’s scheme of work.However there were many successful activities in the scheme. Students worked well on the practical activities and were able to satisfactorily answer examination questions on the topic at the end of the topic. There were several activities that they found particularly useful, for various reasons. The ‘super capacitor’ demonstration certainly caught their interest and was easily remembered later when looking at why each capacitor has a maximum voltage it can withstand. The ‘potential difference in colour’ activity (adapted from Reeves, 2003) was especially useful to several students who said that they often had trouble identifying from circuit diagrams what types of circuits they were looking at, and therefore which would have more potential difference or brighter bulbs. They found that the activity gave them a new way of looking at what happened in the circuit, although in fact it just reinforces the basic ideas that they already know). The ‘solitaire’ exponential homework task (Jones, 2006) was also surprisingly popular, and allowing the students to play a game to get data to look at worked as a simple bribe for them to complete their home work!I found it difficult to avoid emphasising the maths in order to concentrate on the understanding. Indeed when I did this one of the students commented that they just wanted to know what the equations were and how to use them. Unfortunately this is a by-product with the examination system that I have seen before lower down in the schooling system. Students know that they need to be able to do the maths to score well in the exam and can confuse this with the idea that they understand what is going on. It is difficult to avoid putting in exam questions as a starter or plenary, as you do want to check that they will be able to perform in the examination however this can negate the power of the understanding emphasis of the lesson – students can still go away with the idea that all they need to be able to do is to plug some numbers into the calculator.

This is also illustrated by the high average end of unit test scores which I feel do not accurately convey the basic misconceptions that students still carried. I feel I need to work this issue lower down the school, to try to get over the idea that taking time to understand is a useful thing to do, and will make life easier in the long run. I also need to retrain myself to avoid overemphasising the mathematics when I approach a syllabus.I asked for suggestions for improvement from both staff and students (Appendix B). The students suggested that I go to see the maths staff for information on how they teach natural logs and exponentials as it was different from the approach used by me. They said that this conflict had been an issue on several occasions throughout their schooling, although there were differing views as to its impact. Some students got confused by the differences, whereas others found the two different ways of looking at the same thing to be useful. Both staff commented favourably on the scheme of work as a whole, agreeing to adopt it as the department scheme. Their additional comments reflected their wider experience. One teacher commented on the need to give students at this level more scope to enable them to work independently through practical tasks, allowing them to explore for themselves the various factors involved. I think that for me to be comfortable with this approach I need to have taught the topic once through already so that I know the various pitfalls and issues so that I can point the students in the right direction, ensure that I know the content well enough and have the confidence to allow students to have their head. I still struggle with the being able to anticipate all the possible problems and questions in a topic so that I can feel prepared for each lesson, which obviously came across in my teaching. This was also noted by one teacher, who noticed errors in my use of terminology, which of course could only add to the confusion already shown by the students own written and verbal answers. In fact there will still be issues that have not yet been raised which will only crop up when I teach this section again, so this is still clearly a work in progress.

Section B Reflections on my learning journey.

Development of personal subject knowledge

Prior to taking part in the SASP course I was out of my depth teaching A level physics without even a GCSE in that subject to my name. In my own schooldays I had studied integrated science at GCSE. I had not taken up physics at A level as I was not allowed to link it with biology and chemistry. Therefore when I began my first teaching placements and subsequent posts, I had a lot to try to remember. Consequently I found myself sitting in on A level lessons during my free lessons in order to try to fill in the gaps in my knowledge. I was blessed with an excellent head of physics when I

joined my current school, and his enthusiasm kindled my own. As time went on, due to the lack of physics teachers typical in many schools at the moment, I was encouraged to try my hand at a little teaching. This state of affairs has continued over the last 5 years or so, without any formal training. I have been on the look out for something like the SASP course for a while, conscious that I was doing my students a disservice with my partial knowledge of the subject. My knowledge of mathematics has enabled me to ‘get by’ in physics however I was more than aware that my ability to explain what is going on was poor. However until I started on this course I had no conception of the fundamental flaws in my knowledge of much of the basic key stage three and four information that I considered I had full command of. This was brought home to me from the outset during the diagnostic test we took part in on the first session – several questions contained what I thought was very simple ideas that I was confident about, however I had the answers wrong. Indeed I had to discuss one question on the total force acting on a ball with several different people before I realised where I was going wrong – a simple misunderstanding of the concept where the ball can be travelling up even if the overall force is down as long as it is decelerating. The worrying thing is that I had been conveying that idea poorly for almost 10 years! It wasn’t until we had completed the work on this on day three of the course that I felt able to apply the knowledge confidently to new situations. Every time I look at one of those questions now I remember to only look at the forces acting on the object (rather than those caused by the object), and to draw simplified diagram consisting of a circle, which made the whole process much quicker and clearer, and I have been able to pass this on to the students. It also gave me a much easier way to help explain Newton’s first law (one that students always have trouble with), by showing the forces on the diagram and then showing that if you decrease the counter forces the size of the force you need to put in to keep going at the same speed decreases until theoretically if you could eliminate the counter forces you would keep going forever.However, such is the nature of physics that research has shown that even very experienced physics teachers can think they know what they are talking about in some areas until they are pressed to explain (Gunstone et al, 2009), at which point their confidence and knowledge evaporates. The same study also showed that different teachers can have very different perceptions of the topic and of how to use the terminology, and therefore if students come across several different members of staff over their time at school (a fairly likely event) it is not surprising that they are a little confused as to the meanings of the terminology, never mind the ideas the terminology is used to convey. Not only this, but in a subject where analogy is often used, it can be easy for students to assume that we mean something that we don’t (Taber, 2005), or to pick up meanings from colloquial usage.

Of course many of the topics were completely new to me – for example I had no idea what semi-conductors were used for or how they worked before the SASP course, and I had no knowledge of how forces developed in the A level syllabus. Indeed forces was one of the big areas I have struggled with this year, firstly with the issues relating to basic Newton’s laws that I thought I knew about but obviously didn’t, then work on circular motion and gravitation revealed that although I had now picked up the basics I was not really able to reapply the concepts easily. In hindsight the most valuable changes to my subject knowledge have been those that have ironed out my own basic misconceptions and consequently have made me more aware of those misconceptions in others. This is because I feel this will have the biggest impact on the learning of the students in my school. However whilst progressing through the course, there were several topics covered in which I had always drawn a blank in my mind. With topics such as waves and the Youngs slit experiments I had always had a mental block. I just couldn’t get the idea of what the actual lines were representing and why the patterns at the ends were so significant. A diffraction slits diagram which can be held up to your eyes to see the pattern really made it all fall into place for me, and after a few great demos in the ripple tank (which previously I had never felt confident enough to set up or use) and laser pointers I felt that I would be able to explain the significance of the experiments and theory to my students. One aspect that would have been of use to almost any physics teacher, never mind a non-specialist, would have been the sessions on cutting edge physics such as the work on quantum and particle physics and the session on physics at work in the British museum. Not only can I pass this information onto students to try to enthuse them with the subject, but it has also been great to go back and share this not only with other faculty members in general, but also the physicists in particular, as many advances in these fields were made long after they left university.Many of the things that I felt were most valuable were not necessarily actual teaching points themselves. Some gave me information to enhance the students learning, for example being able to explain the difference between English, European and American plugs. Others revealed areas to avoid to prevent confusion, for example not to add too many bulbs in parallel as although they should remain same brightness they wont due to the fact that real power supplies cannot maintain their terminal voltage when they source larger currents due to too much internal resistance. The course has also reminded me that although something may look complicated or new, using common sense can help to make sense of it. For example the idea that often if you convert an equation to the form y = mx + c you can then use data from an experiment to draw a graph and work out a value for ‘m’, or using logarithms to

get approximations to quickly work out if answers are in the correct order of magnitude - it is tricks like these that often make physicists seem so clever and now I know how to do it too! Also when we looked at alternative forms of energy as possible resources for the future, I had always thought wind energy would be great for the UK because I had not stopped to consider where the turbines would all go and matters such as the volume of concrete required to make them and the costs of maintenance.

The impact of different pedagogical approaches on pupils learning

I think the main change to my teaching style that I will take away with me is an aspect that I currently share with many non specialists, that is a tendency to rush in with the maths first so that students can often perform the calculations but cannot say why they are doing it, or understand the underlying principles. This means that their knowledge is too superficial to enable them to apply it in other areas and they are unlikely to see its importance or relevance to other areas. Having tried the alternate approach of allowing students to work things out for themselves I have now learnt not to do that and have seen the benefits from both Key Stage Four (energy) and Key Stag Five (capacitors) topics. I noticed it myself when we looked at subjects on the course that I had already taught at A level. I could grasp the ideas more easily as I did not have to worry about the maths.This does need to be a style that is adopted early to reap the biggest rewards, as I can see from my own experiences that a lack of understanding further down can be covered up yet still used as a foundation for future ideas as you progress. As a result of being closely observed by other physicists – something that did not often occur before as neither is my line manager – I have learnt to avoid being overprepared and to try to let students work through things themselves instead.I think in several cases we also need to reassess the level to which we teach certain students. Students get frustrated being taught something only to learn later that it is wrong – for example with forces we usually start by looking at the forward force provided by the engine when we should be looking at the forward force of the ground pushing against the car – this is quite easy to explain and would avoid issues such as students being confused by forces acting on the object as opposed to forces provided by the object. I have realised letting students discover ideas for themselves by giving them the evidence they can use to come to terms with big ideas is worth the trouble required to set up the necessary experiments. I also saw first hand that it was important not to explain things to students before they have the chance to try to work it out for themselves, especially in practical situations. In one experiment on the SASP course I didn’t understand what was going

on as I missed the introduction. Someone told me the answer but I didn’t connect with it - in my notes it is written in as the potato experiment but I have no recollection of it at all.It wasn’t until we actually thought about it on the course that I realised that one of the biggest ideas in science - that everything is made of atoms (Feynman, 1998) - is backed up by very little direct evidence. Students are just expected to ‘believe’, in our school at any rate, that this is the case. Although I wasn’t teaching the relevant topic at the time I put it in for a Year 9 class as an end of term activity. We tried a smoke cell and pollen grains and they were fascinated by what they saw. They also tried a simplified oil droplet experiment and were really excited when I explained that the oil was one molecule thick. I was amazed that they could draw so much awe and wonder from something that was intellectually stimulating rather than the usual explosion, which shows how easy it is to underestimate your students, and how wrong you can be when you try to second guess what they will find interesting.

Affect of responses to different teaching approaches Of most impact have been the outstanding new ideas for activities to use in the classroom, from both the tutor and other members of the course. My favourites include some very simple ideas and models to get information across without misconceptions, such as showing where the kinetic energy goes during elastic and inelastic collisions by using bouncy balls in a plastic beaker so that you can see the random motion of the balls in the beaker and equate it to energy being transformed into thermal energy. I found this especially useful as it helps explain something you cannot normally see, a tool needed often in physics, in a simple and ‘obvious when you know how’ way. Other examples that evoked cries of ‘oh I see what you mean’ from students included using a sparkler to show forces in circular motion and the balloon taped to a straw shooting across the room to show momentum. I confess I was not teaching circular motion or momentum at the time I demonstrated these experiments, but just thought I would show it to students to see if they could make the connection, and was delighted with the result. These have also given me the means and encouragement to go and look up more practicals, for example using the practical physics website. I have noticed that (unsurprisingly) when I take the time to research the topic and find out interesting and relevant information the students are in turn more interested and therefore more likely to grasp new ideas. This did not always work, for example in a chemistry lesson I used marshmallows and toothpicks to explain the difference between alkanes and alkenes. This did not work well as students just played around. With hindsight the timing not great (Thursday period 5) and maybe the use of new food was too tempting. However when I looked up some IR pictures to show students studying radiation, the arrival of a picture of a zebra

caused much excitement as they first worked out that it was a zebra and then worked out how that they knew it was. Another interesting point was that students had no real idea of the scientists behind the discoveries. In future I will look at the ideas put forward by Hadzigeorgiou (2006) and Stinner (1995) to humanise science by telling the story so students have a wider knowledge and are more interested. For example tales such as James Joule measuring the temperature of water in waterfalls on his honeymoon or the church being mad with Galileo because he wrote about his ideas in Italian rather than Latin so that anyone could read it, or Edison trying to discredit AC by using it to electrocute an elephant are fascinating and help to reinforce the idea that scientists are just people too, and that students can aspire to be like them (although not to the extent of copying any of the examples given here of course).Unsurprisingly this works well at keeping students’ attention when the information is funny or risqué, and short. However it does not always work when you try to mould an activity around it. I used an activity that we had looked at on the course based on Boyles Law lesson. Students were given an information sheet which looked at the ‘squashability of gases’ by looking at a passage from a French textbook and some of Boyle’s own notes to try to introduce the ideas in a different way. The students’ response to this was mixed. Although most thought it was a nice idea to be introduced to these ideas some still indoctrinated with the ‘is it in the test’ mindset. One aspect of science teaching that I never liked is data logging. Prior to the course it has just seemed to be a lot of effort for no real benefit, and often just being done for the sake of it. However the two sessions spent on this, together with other practicals during length of the course have changed my mind, and I can especially see the use of this sort of equipment for A level physics practical sessions. One other use I particularly liked was the idea of being able to give students an electronic copy of a graph of results to annotate in class or at home – I used this successfully with a group of A level biologists.

Changes to the way I facilitate pupil learning Quite early on I realised that in normal teaching I just assumed students had brought forward required knowledge from previous lessons. I didn’t think about the complexities of the information they may have received that would lead to that point. I also didn’t always take time to check at the start of a topic and therefore didn’t actually know what information they came with. In this way I will often be losing students at the start who then never catch up. So I have been making an effort to spend some time ensuring students have the knowledge they need before I start a new topic. This has taken up time which can be tricky when you are trying to fit things in before exam deadlines, however there is no point spending time teaching something if many of the students are not able to

progress. The course has made me appreciate the importance of looking at how the ideas are introduced at Key Stage Two and are then developed through the secondary school curriculum. Before I just went ahead and taught it without even thinking about the foundations (and possible misconceptions) students brought except for a few specific instances (for example breathing and respiration which are biology-related).I am also making sure that I include more active learning so that students can learn not only in a way that increases their knowledge but also that ensures they can use that information to help them understand the world in a way that they couldn’t before. I have seen from my other assignments that simply telling students things doesn’t remove misconceptions. Instead they stick in the mind because they explain the physics in a way that makes sense to students, often by relating it to existing knowledge. So I need to try to let students work things out for themselves, whilst giving them things that makes sense to hang reality on. Once they understand what is going on they can then formalise this thought into an equation if necessary. I know how easy it is to allow previous ideas to cloud new ones, for example I got stuck on the idea that the more massive the object the stronger gravitational field it has. I couldn’t then resolve ideas of gravity between sun and earth, (that is the forces have to be equal and opposite) with the idea that is the sun is larger it must exerts more of a pull on us than we on it. I know the relevant physics but was reluctant to apply it as it didn’t seem to fit. Luckily I also now have many more quick experiments in my repertoire that students can use to help work things out for themselves. Simple ideas that make a point such as holding a bit of tin foil round both ends of a battery and feeling it heat up as a quick example of the heating effect of current, winding string round a coat hanger and putting it in your ears to show how well sound travels through solids, or using thermo-chromic film affixed to a globe to demonstrate that the equator is hotter than the poles, or attached to a bicycle pump to show how decreasing the volume of a gas will increase its temperature.Increased confidence is one of the things that this course has given me. I can now think about things more calmly and work things out rather than panicking and guessing. Although I am not yet in the happy position to want my students to ask me questions that I can’t answer, thanks to the course I am in a better position to deal with it when it occurs.Confidence especially applies when using physics equipment, particularly activities that before I would have ignored because I didn’t know where to start when setting them up. I am now able to breathe more life into old experiments such as the Van de Graaf, by using it to lighting a bunsen making the pie cases fly off, or lighting a fluorescent tube. Not only does this engage with students who are jaded as they have seen it before but I can also explain fully what is going on.

I can now use the equipment in the knowledge that I have the ability to troubleshoot when things go wrong, both for standalone equipment such as the air track, electron diffraction tube and ripple tank, and also for general things such as using a multi-meter to identify faulty equipment in electrical circuits. I have also picked up simple safety ideas for example clipping metal electrodes to the side of the beaker to stop them crossing. It is all these simple short cuts that are second nature to a proper physicist that I did not know before as you don’t find them in the textbooks. An additional benefit is that I now have a network of people to ask outside my school for advice, which is especially fortunate with my head of physics leaving this summer. I will also make more use of animations from the many we have been shown this year. Some were good to use for demonstration purposes, such as the balloon showing charges, which was excellent to show why charged things attract neutral objects, and others, such as the many Phet animations, are useful to allow students to explore on their own. I will do the same with video clips as the ones I saw on the course finally persuaded to work out how to get around the You tube block we have on our school network. A favourite that I tried this year was the MIT one of balloon animals deflating and re-inflating as they were put into liquid nitrogen and subsequently removed. I even had students from another Year 10 class begging to be allowed to see it and even staying behind at break to do so!Videos and animations often help in another area, that of giving relevance to the curriculum. Interesting anecdotes are a feature of my biology teaching which students find interesting and I felt that my physics teaching was suffering in their absence. Now, thanks to the tutors I can drop in many fascinating facts, such as why popcorn jumps when it pops, why motorways are slightly curved in cross section, why the water in a toilet bowl moves up and down on windy days, why a straw can puncture a potato if stabbed swiftly, how much mass a matchbox full of matter would have and how Polaroids work. Again these are the things that make me feel more confident in my teaching – the ability to make the physics relevant and use it to explain the world as we know it. Sitting in other physics teachers lessons it has always been this that I have aspired to, as it really inspires students and reminds them how useful physics can be.Now my confidence has increased I feel I am able to use thought experiments with the students. I really like these as it shows students how scientists could make such groundbreaking laws without the technology that we have at our fingertips today and lets them see that they too can think in the same way. Aside from all the knowledge and understanding I have gained, it has been a good experience to be a learner again. It has made me more aware of how the students feel, for example if I had prepared for a lesson then I felt more at ease with what was happening. I found myself more easily engaged at certain times of the day even though I was interested in everything. I was also reminded how

useful trips can be. I had just come to think of them as a mountain of paper work, but after going back stage in the British Museum you can see how trips inspire students. It can also give them career ideas and be able to see what physics can do in the real world.Returning to learning myself, it was also easy to see why some students just want notes in their books and don’t want to think, as it takes them out of their comfort zone where there is the chance they can get things wrong. I learnt that if I let them do this in small groups rather than as a whole they will interact more readily, as we showed when we were asked to share our schemes of work with others. It has also helped to reengage my enthusiasm for physics and science in general. I have used many of the internet links to show my form for ‘science’ registration Tuesdays (for example Adam Hart Davies wearing a faraday suit to allow him to touch 500000V, or the Rubens tube experiment) which was so popular it even had other students coming into watch and offering clips of their own we could try. One thing said on the course that really struck a chord, with both my students and myself, was the phrase ‘dogs don’t do this’. pete in said it in reference to Ptolemy’s geocentric model and how great humans are to be able to get out into the universe just by thinking. A lot is said about having ‘awe and wonder’ in lessons, but it doesn’t need to be all whiz-bangs; it can just be reminding students how amazing it is that we as a species can do these things.The great thing about this course is that it has not just helped me, but it is also helping the rest of the department. As I am coming from a biology point of view I can sometimes explain ideas to non-physicists more successfully as I know what the stumbling blocks to understanding are. I cannot do this so readily with maths or biology as I often cannot see the problems. Now that I have the rudiments of knowledge, and increased confidence, I have been happier helping others and running workshops on what I do know. There is obviously still more to do. I still have many areas in which I am unsure, for example I am not comfortable with what an arc second is and field lines still worry me, but I now know that as I work on things they do get clearer. I know this sounds obvious, however before the course I (in common with many other students and non-specialists) just put vast areas of physics into a box in my head labelled ‘too hard – ignore’. I now know where to find the answers, and that with hard work I will get there eventually. The important thing is that I am no longer so overwhelmed that I give up before I start. The fact that I don’t know everything is what makes physics so exciting, as it means that the boundaries are always moving.

BibliographyAshmann, S. (2009) The Pennies-as-Electrons Analogy. Science and Children, 47(4): 24 - 28

Driver, R., Guesne, E. and Tiberghien, A. (1993) Children’s Ideas and the Learning of Science. In R Driver, E Guesne and A Tiberghien (eds.) Children’s ideas in Science (pp.33-51). Open University Press.

Driver, R., Guesne, E. and Tiberghien, A. (1993)2 Some features of children’s ideas and their implications for teaching. In R Driver, E Guesne and A Tiberghien (eds.) Children’s ideas in Science (pp.193-201). Open University Press.

Driver, R., Squires, A., Rushworth, P. and Wood-Robinson, V. (2008) Making sense of secondary science – research into children’s ideas RoutledgeFalmer

Ehrlich, R. (1990) Turning the World Inside Out. Princeton University Press

Emmett, K., Klaassen, K. and Eijkelhof, H (2009) Fast feedback in classroom practice. Physics Education, 44: 246-252

Engel Clough, E. and Driver, R. (1985) Secondary students’ conceptions of the conduction of heat: bringing together scientific and personal views. Physics Education, 20: 176-182

Eylon, B. and Ganiel, U. (1990) Macro-micro relationships: the missing link between electrostatics and electrodynamics in students’ reasoning. International Journal of Science Education, 12(1): 79-94

Feynman, R. (1998) Six Easy Pieces London: Penguin

Gunstone, R., Mulhall, P. and McKittrick, B. (2009) Physics teachers’ perceptions of the difficulty of teaching electricity. Research into Science Education, 39:515-538

Hadzigeorgiou, Y. (2006) Humanizing the teaching of physics through storytelling: the case of current electricity. Physics Education, 41(1): 42-46

Hartel, H. (1982) The Electric Circuit as a System: A New Approach. European Journal of Science Education, 4(1): 45 – 55

Jerram, A. (1999) Teaching Physics to KS4 . Bath: Hodder & Stoughton.

Jones, S. (2006) Bouncing playing cards help to explain exponential relationship. Physics Education, 41:486

Michael Watts, D. and Gilbert, J.K. (1983) Enigmas in School Science: students’ conceptions for scientifically associated words, Research in Science and Technological Education, 1 (2): 161-171

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Appendix A (lesson plans and resources)The Lesson Plan

Year 13 – Capacitors – SOW Lesson 1

Literacy / Numeracy /ICT ObjectivesUse of keywords Simple maths

Key WordsCharge, potential difference, e.m.f., current, resistance,

Time

5

5

20

15

15

Teaching Input

Register the classObjective of the lesson (on board)

StarterDemo – glowing gherkin – ask students to describe what is happening

IntroductionGet students to try the questionnaire, based on KS3 / KS4 LO’s and common misconceptions suggested by research (books – ASE Guide to Secondary Education, M Ratcliffe (ed), Making sense of secondary science – research into children’s ideas Driver, Squires, Rushworth, & Wood-Robinson (eds.) also http://homepage.mac.com/vtalsma/syllabi/2943/handouts/misconcept.html~top

DevelopmentStudents to discuss their answers and try to work out group answers, with staff intervention to ensure correct ideas are in place

PlenaryQuestions taken from QI (TV programme http://www.youtube.com/watch?v=sZkhTesX_M0 ) – students to discuss the answers they would give and suggest those words / phrases that would loose them points – once students have discussed it show them the answers of the panellists

Specific Learning Outcomes

To be able to recall basic facts about electricity including definitions of terminology and relationships between factors such as current, p.d. and resistance

To remind students that its not just negative charges that carry electricity

To iron out issues caused by misconceptions by identifying them and reminding students of the correct ideas

As above

Idea of speed of electron flow

Resources

Power pack, leads, metal electrodes, gherkin, safety screen

Questionnaire

Computer / screen

DifferentiationTargeted questioningOpen ended questionsExtra, more difficult questions available for higher ability students

http://www.youtube.com/watch?v=sZkhTesX_M0

http://www.youtube.com/watch?v=sZkhTesX_M0

Home LearningPotential difference in colour sheet

Set Due In

Questionnaire:

Electricity ideas

For these questions, you are firstly going to answer them yourself and say how confident you are with your answer. Then you are to discuss your ideas with others in your group in order to correct any mistakes, and consider any issues that arise. Jot down any ways in which your ideas change.

1. In the table below, fill in the missing symbols, units and other information:

Value Symbol Unit How to measure itCurrent

Potential difference

e.m.f.

Charge

Resistance

Confidence scale:a) I am sure I am rightb) I am fairly confidentc) I am not very confidentd) I am just guessing

2. For each of the following, describe what their role in as circuit is:Value DescriptionCurrent

Potential differencee.m.f.

Charge

Resistance

Confidence scale:a) I am sure I am rightb) I am fairly confident

c) I am not very confidentd) I am just guessing

3. Electricity is…


4. In the space below, sketch a graph showing an exponential relationship:


5. Give an example of an exponential increase and an exponential decrease: Increase: Decrease:

Confidence scale: a) I am sure I am right

b) I am fairly confidentc) I am not very confidentd) I am just guessing

6. Mark these statements either ‘true’ or ‘false’: Electricity is made up of a flow of electrons TRUE / FALSE

Electricity carries zero mass TRUE / FALSE

Electrons move through wires at nearly the speed of light TRUE /

FALSE

High voltage is dangerous TRUE / FALSE

Voltage can occur independently of current TRUE / FALSE

Confidence scale: a) I am sure I am right

b) I am fairly confidentc) I am not very confidentd) I am just guessing

7. For the following analogies of the flow of electricity around a circuit, state what represents the cell, wires, current and energy, and state a limitation of the analogy

Water flowing around a central heating system

Sack of coal being delivered to houses

Cell represented by…

Wires represented by …

Current represented by…

Energy represented by …

Limitation …


8. Radioactive decay is known to decay exponentially. What do we mean by exponential decay?


9. A capacitor is a component that can be used to store and release electricity by building up a charge across it. Explain how building up a charge will allow it to store electrical energy and give a use for such a component.


10. Give the value in seconds of the following:1ps

230µs

Confidence scale:a) I am sure I am righte) I am fairly confidentf) I am not very confidentg) I am just guessing

The Lesson Plan



Key WordsCapacitors, capacitance, Fahrads, potential difference, charge

Time

5

5

20

15

15

Teaching Input


StarterTell students that capacitors store energy. Then get them to suggest why they might be found in a) cameras and b) computers

IntroductionExplain structure of capacitorGet students to set up a circuit with a capacitor in to get an idea of how they work

DevelopmentIntroduction of capacitance and the mathematical relationship between it, potential difference and charge

PlenarySuper capacitor demonstration – students watch the demo and discuss uses (teacher led)


To be able to describe the uses of capacitors and to be able to set up a circuit with one in

To put todays work into context

Students identify how the current changes as a capacitor charges and discharges

Q = CV

Idea of why there is a voltage limit for capacitors, explore possible uses for super capacitors in the future

Resources

Capacitors, milli-ammeters, wires, croc clips, power pack

Sheet 60S from the old OCR B Advancing physics scheme

EHT, Tin foil, cling film, wires, croc clips


Home LearningFind out why they use giant capacitors in FERMILAB in the US

Set Due In

The Lesson Plan




Time

5

5

20

20

10

Teaching Input


StarterSheet practicing Q=CV equation from yesterday, and ideas from super capacitor, or sheet from old OCR B SOW ‘Short questions on charging capacitors’

IntroductionStudents set up capacitor circuit but this time they measure the potential difference across the capacitor instead of the current in the circuit – what do they notice? How could they use this information to calculate the energy stored on the capacitor?

Development

Get them to sketch the graph of p.d. against Q from the experiment and from this work out what the equation for energy stored in a capacitor would be (W = ½QV) either from the idea of the area under the graph or from the idea of needing to use average p.d.

Then get them to use yesterdays equations to make up other equations of the same form (eg W = ½CV2)Then try some calcuations

PlenaryShow students a flash on a camera (nice to have photo for use on open day!) – to make point about energy stored Often in text books (indeed in theirs) it states that capacitors store charge – get them to explain why it is misleading to say that capacitors store charge rather than energyThen ask students to fit their ideas of capacitors into the existing models of electricity that they know – complete for HW


To be able to calculate the energy stored in a capacitor

Recap of yesterdays LOs

As the charge builds up on the capacitor, the p.d across it increasesHopefully they should be able to recall the KS4 equation E = QV

Ability to recall and manipulate equations dealing with the energy stored on a capacitor

Resources

Sheet

Capacitors, wires, croc clips, voltmeters, power packs

Sheet 110S from the old OCR B Advancing physics scheme

One use camera with flash


Home LearningSee plenary or sheet 120S from old OCR advancing physics scheme – Energy to and from capacitors

Set Due In

The Lesson Plan




Time

5

5

20

15

15

Teaching Input


Starter

To recall the patterns for calculating the total resistance for resistors linked in series and in parallel

Introduction

Introduce the patterns for capacitors and try to get the students to explain why they work the way they do (eg capacitors in parallel , its like having a bigger capacitor with bigger plates – so it can ‘store’ more charge for a given voltage). Students do a few simple calculations on this theme – draw out a few circuits with 200 and 300µF capacitors in various arrangements

Development

Students then complete the sheet they had as a starter and see if they can explain the comparison between capacitors and resistors

PlenaryStudents use knowledge gained to work out total capacitance in various capacitor networks – eg say you have some 100 µF capacitors – how would you connect them to get a total capacitance of 400µF, 25 µF and 250 µF. Or you have a 100pF, a 200pF and a 600pF capacitor – which arrangement will give the highest/lowest combined capacitance?Students then design a network and calculate its capacitance – these are then swapped for students to work out for home work


To be able to calculate the total capacitance of capacitors in series, parallel and in combination. To be able to explain the difference in these patterns compared to those found with resistors

Series: RT = R1 + R2 etcParallel: 1/ RT = 1/R1 + 1/R2 etc

Series: 1/ CT = 1/C1 + 1/C2 etcParallel: CT = C1 + C2 etc

Reciprocal formula applies to capacitors in series but resistors in parallel – because capacitance indicates how good a capacitor is at storing charge, where s resistance indicates how bad a resistor is at letting current through

Students practice using the formula in more complex situations

Resources

Sheet


Home LearningWork out the capacitance of a friends network

Set Due In

The Lesson Plan


Literacy / Numeracy /ICT ObjectivesUse of keywords Exponential maths

Key WordsCapacitors, capacitance, Fahrads, potential difference, charge, exponential

Time

5

5

20

15

15

Teaching Input


StarterForest fires computer programme - students try to predict each time if the forest will burnRabbits computer programme – students try to sketch graphs of population growth and then criticize the rulesIf time, students try to work out the critical density for total fire / population explosion

IntroductionWater clock experiment or dice experiment

Development

Students use previous experimental knowledge to sketch charge and discharge graphs for Q against t and I against tThey then use this info and the water clock data to look at how resistance, p.d. and capacitance effect rate of discharge

PlenaryExam question based on the water clock


To be able to understand exponential changes

Students start to think about exponential changes

Students use a simple experiment to collect some exponential data

Students use the water experiment data that they can see and understand to explain the more obscure ideas behind the capacitor discharge data

Resources

Computer with old advancing physics A2 disc or world maker loaded plus prompt sheet

Clamp stand, biurette, water, food colouring (optional), beaker, stopwatch, sheet or 100die plus sheet

Sheets

Sheet


Home Learning Set Due In

The Lesson Plan




Time

5

5

20

15

15

Teaching Input


Starter

Capacitance crossword

IntroductionLook at the general formula behind any exponential - use Maths for Science p119-121 to help. Relate to what they already know for radioactivity. Ensure students know how to use their calculators appropriately – use help sheet if necessary

DevelopmentAllow students to try problems on their own – either use the textbook ones which are rather good or Sheet 140S from the old OCR B Advancing scheme

PlenarySummary questions for students to try alone and then peer mark – based on graphical interpretations of events when a capacitor charges / discharges (from a SOW I saw used when I was in New Zealand)


To be able to apply the idea of exponential change to capacitor charge and discharge, and to be able to use the charge / discharge exponential equations

Recap of knowledge so far in the chapter

To be able to explain what it means to say a capacitor charges / discharges exponentially and what this actually means

To be able to use the charge / discharge exponential equations

To be able to explain what they have learnt to others

Resources

Sheet

Sheet

Sheet



The Lesson Plan




Time

5

10

15

15

15

Teaching Input


Starter

Snowballs - Students write a definition for exponential change, then screw up the paper and throw to another student. They open the paper and add some more detail, and make changes if what has been written is incorrect (in a different colour). This is repeated again (and again if possible). Finally students get their original back. Class discuss what is written and ensure everyone has the correct idea

Introduction

Students explore what the time constant is and how RC can give a measurement of time – relate back to the exponential function and to students work on radioactivity to give them something to compare it to. Give the students the relevant equations and allow them to work it out for themselves. Advancing physics for you (Johnstone) has a nice spread on this on p270-271The worksheet Discharging a capacitor has an alternate route and is also worth doing

DevelopmentStudents try simple questions to see if they can manipulate the equations

PlenaryExam questions based on the time constant and the exponential function


To be able to calculate the time constant and understand what it represents

Know how to define an exponential relationship (with particular reference to capacitance)

To understand what RC represents

To be able to calculate the time constant

Reinforce knowledge

Resources

Scrap paper

Sheet from old OCR B scheme – ‘Discharging a capacitor 80S’

Sheet from old OCR B scheme – ‘Discharge and time constants 70S’

Exam questions


Home LearningRevise for exam next lesson

Set Due In

The Lesson Plan


Literacy / Numeracy /ICT ObjectivesUse of keywords Simple mathsExponential maths


Time

5

5

25

10

15

Teaching Input


Starter

On board go through the equations / values that they are given in the exam – students can discuss this once they have guessed them all

IntroductionExam questions to be completed in exam conditions

Development

Students peer mark and try to agree on a set of answers

PlenaryStudents are given correct answers and have to correct their own mistakes


To be able to show an understanding of the concepts in this unit

Resources

Exam paper



Appendix B (feedback)

Feedback from teacher A:Thank you for the opportunity to visit one of your lessons again, and to work with you on teaching these rather tricky parts of the syllabus! It was interesting and informative for me, and I apologise in advance for the brevity of my response – I am afraid reports are upon us once again!

I had a look at the questionnaire which you designed to introduce this topic and there were certainly some challenging questions in there. I thought that question 3 was maybe a little too vague; most students will opt for an easy response. Question 6 was intriguing but I am not sure of its relevance. Your rapport with the students is very good, however you did seem more nervous than before when I watched you with the year ten class. You appeared to lose your way with some of the definitions and you need to take care with your use of scientific terminology. Although the mistakes you made were casual mistakes, and most of the time you corrected yourself, students can become confused very easily. For example on several occasions you used ‘current’ instead of ‘charge’. This was followed by students doing the same thing. Go slowly through the work and ensure that you think before you speak!The dice practical and the computer modelling you showed me worked well, although the worldmaker programme is probably only useful for an introduction – too many of the programmes are too similar to be of interest now that modelling as such has been removed from the syllabus. The results we achieved from the dice were actually very good, and enabled us to complete some worthwhile analysis. I hope you got that copy of a sheet I made on the mathematics relating to exponential radioactive decay that I gave to X to pass on – it does look rather complicated however the students worked through it very well and seemed to gain understanding from it. It may be of some use to you - feel free to use it in the scheme if you wish.Thank you once again – it was enjoyable and informative – we will have to continue this next year

Feedback from teacher B:Capacitance lessons:Nice practicals but maybe they were a little bit too prescriptive. At this level you can let students get the idea themselves, especially if they have already looked at radioactive decay with X. Your handling of the practical work was good – obviously the practice paid off. It is always worth playing around with the equipment before you get it out for the students. Try to avoid death by worksheet – as you get more confident with the subject matter this should get easier – although the students do

seem to like this approach it doesn’t always stretch them as much. Misconceptions addressed – good, but be aware of your ownNB: Ive seen the super capacitor done with a bin liner – could be good to try – get students to think of the issues with this

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