The Big Ideas in Physics and How to Teach Them provides all of the knowledge and skills you need to teach physics effectively at the secondary level. Each chapter provides the historical narrative behind a Big Idea, explaining its significance, the key figures behind it, and its place in scientific history.
1. THE BIG IDEAS IN PHYSICS AND HOW TO TEACH THEM ‘The book is brilliant. I hope all physics teacher trainers and trainees, as well as established teachers, use this critically important work to guide their teaching.’ John Sweller, Emeritus Professor at the School of Education, The University of New South Wales, Australia The Big Ideas in Physics and How to Teach Them provides all of the knowledge and skills you need to teach physics effectively at secondary level. Each chapter provides the histori- cal narrative behind a Big Idea, explaining its significance, the key figures behind it and its place in scientific history. Accompanied by detailed, ready-to-use lesson plans and classroom activities, the book expertly fuses the ‘what to teach’ and the ‘how to teach it’, creating an invaluable resource which contains not only a thorough explanation of physics, but also the applied pedagogy to ensure its effective translation to students in the classroom. Including a wide range of teaching strategies, archetypal assessment questions and model answers, the book tackles misconceptions and offers succinct and simple explanations of complex topics. Each of the five big ideas in physics are covered in detail: •• electricity •• forces •• energy •• particles •• the universe Aimed at new and trainee physics teachers, particularly non-specialists, this book provides the knowledge and skills you need to teach physics successfully at secondary level, and will inject new life into your physics teaching. Ben Rogers teaches physics and trains new teachers for Paradigm Trust. He is a former lec- turer on the Physics Enhancement Course at the University of East London, UK.
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3. THE BIG IDEAS IN PHYSICS AND HOW TO TEACH THEM Teaching Physics 11–18 Ben Rogers
7. Preface x Acknowledgements xi Introduction 1 Zero A big idea about learning 3 Working memory 3 Long-term memory 4 External environment 4 How can we use Cognitive Load Theory to accelerate learning? 5 Knowledge 10 Archetypal questions 10 Model-based problem solving 11 The privileged status of stories – Willingham 11 Misconceptions – When knowledge is wrong 11 Practical work in physics 13 Reducing Cognitive Load for practical work 13 Literacy – A different sort of physics problem 14 What are the Cognitive Loads associated with reading and how can we reduce them? 14 What are the Cognitive Loads of writing and how can we reduce them? 16 How to teach writing in physics 18 Conclusion 18 1 Electricity 20 Introduction 20 A history of electricity 20 Electricity in the Classroom 36 Misconceptions 38 Archetypal questions 40 Models 40 Model based reasoning 41
8. viii Contents Practical electricity 43 Example lesson plan 44 Conclusion 47 2 Forces at a distance 49 Petrus Peregrinus, Crusader – 1269 50 William Gilbert of Colchester, Physician to Queen Elizabeth I – 1600 50 Newton’s Law of Universal Gravitation – 1687 51 Faraday’s lines of force – 1852 53 Maxwell’s equations: The second great unification in physics – 1865 54 Einstein’s curved space – 1915 55 Fermi’s nuclear forces – 1933 55 Teaching forces at a distance 56 Archetypal questions 58 Using strategies from cognitive psychology in lessons 59 Using demonstrations and practical work for writing 61 Example lesson plan 63 Conclusion 67 3 Energy 69 A short history of five energies 69 Kinetic energy and potential energy: Descartes and Leibniz – 1644 and 1676 70 Chemical energy and heat energy: James Joule – 1843 71 Nuclear energy: E = mc2 – 1905 72 Teaching energy 73 Types of energy – stores and pathways 73 Misconceptions 73 Archetypal questions 74 Using strategies from cognitive psychology in lessons 76 Reading and writing 76 Reducing Cognitive Load 77 Example lesson plan 77 Conclusion 85 4 Particles 87 Introduction 87 A history of particles 87 But atoms are not real. Or are they? Einstein – 1904 89 Rays, beams and other phenomena – 1869 to 1899 91 Pieces of atoms – 1897 to 1899 92 Disproof of the pudding: Rutherford’s astonishing career – 1900 to 1921 93 Neutrons and war – 1932 to 1945 95 Teaching particles 96
9. Contents ix Misconceptions 96 Archetypal questions 97 Useful strategies from cognitive psychology in lessons 99 Example lesson plan 101 Conclusion 105 Notes 105 5 The universe 107 Introduction 107 The telescope – 1608 110 Teaching the universe 115 Misconceptions 115 Archetypal questions 117 Models 118 Practical astronomy 123 Example lesson plan 126 Conclusion 129 Bibliography 130 Index 133
10. This book is written for every new physics teacher, whether you are new to teaching or new to teaching physics. Recruiting new physics teachers is difficult. In 2015/16 in England: •• 29% of the 1,055 physics training places were unfilled. •• 28% of physics lessons were taught by teachers without post A-level experience. (DfE 2016) The initial idea for the structure of this book came from a report published in 2010 by the Association of Science Education (ASE): ‘The Principles and Big Ideas of Science Education’, edited by Wynne Harlen. The report identified fourteen ‘Big Ideas’ of science education. I have fewer big ideas for physics teachers. The ideas I have chosen are electricity, forces at a distance, energy, particles and the universe. Each of these big ideas has its own stories and its own pedagogy. This book has a chapter for each. But the book starts with a different sort of big idea: a learning theory. I have used John Sweller’s Cognitive Load Theory to explain why I have chosen specific activities and approaches. Whether you are an experienced teacher, teaching physics for the first time or new to the profession, thank you. My aim is to help you enjoy teaching physics and to teach it well.
11. This book began as a physics knowledge enhancement course at Thetford Academy. I got to work with enthusiastic, skilled teachers who were teaching physics but who weren’t experi- enced physics teachers. I want to thank Adrian Ball for initiating the course and for encourag- ing me to write the book, and all of the participants of the course for their encouragement and feedback. The narrative element of the book was developed from a discussion with Daisy Christodoulou about the importance of narrative in learning. We wanted a text which told the narratives of science, something like Bill Bryson’s A Short History of Nearly Everything but aligned with the curriculum. Half of this book is dedicated to those narratives. I would like to thank Alan Weller of UEL for guiding me through the early stages of finding a publisher and Bill Holledge of Paradigm Trust, Dr Jo Saxton of Turner Schools and Tony Sherborne of the Centre for Science Education, Sheffield Hallam University for helping me clear the first hurdles. I am grateful for generous feedback on the first chapter from Professor Dylan Wiliam and Professor John Sweller. The errors which remain are my own. My thanks also to Dr Lucy Rogers, Richard Heald and Simon Laycock for their feedback on the writing and their encouragement. Finally, I owe so much in my life and career to Denise Dickinson, who has been by my side since I first learnt to teach, guiding and encouraging me and along the way teaching me to write a little better.
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13. Know how to solve every problem that has been solved. Richard Feynman You are a new physics teacher – you have been asked to teach students how to be physicists. This means teaching students how to become physics problem solvers. A physicist is the sum of the problems she can solve. She knows the conservation of energy when she can solve all of the problems associated with it. Knowing all the problems lets you solve new ones: the science student, confronted with a problem, seeks to see it as like one or more of the exemplary problems he has encountered before. (Kuhn 1977: 297) In other words, to become a better problem solver, a novice physicist needs to be exposed to as many archetypal questions as possible. More than that, she needs to be exposed to archetypal questions in as many guises as possible, until she can see the underlying deep structure of a question. This is a book about solving physics problems. It is about the knowledge a learner needs to become an expert. It is about the archetypal problems every physics student needs to learn. It is about how to teach them as efficiently and effectively as possible. In 1966 Richard Feynman gave an interview about teaching physics. He said that there is usually a problem in physics lessons – the students do not know where they are. His solution: “there always should be some kind of a map” (Feynman 2010: 16). I have constructed this book around a map. I started by writing the stories around a time- line for five big ideas of physics: electricity, forces at a distance, energy, particles and the universe. Figure i.1 is a map I made of the big ideas of physics. This book is about teaching these five big ideas. Each chapter starts with the story of the big idea. Stories find a way of lodging in our brains. I use the stories as a base to build knowl- edge onto. But before I start with the big ideas of physics, I need to explain about another big idea in this book: a big idea about learning.
14. 2 Introduction 1500 1600 1700 1800 1900 2000 GALVANI/ FRANKLIN VOLTA FARADAY GILBERT OF GUERICKE G RAY MAXWELL COLCHESTER ELECTROSTATIC VON KLEIST/ VAN OERSTED Browne MUSSCHENBROEK EINSTEIN ELECTRICITY (LEYDEN JAR) HERSCHEL CHADWICK MAGNETISM JJ THOMPSON FERMI JOLIOT-CURIE CURIE BOHR EO GALIL RUTHERFORD NEWTON GRAVITY COPERNICUS KEPLER THE METRO-STOPS REPRESENT THE SPACE DALTON PUBLICATION OF AN IMPORTANT TEXT PARTICLES LEIBNIZ ENERGY DU CHÂTELET JOULE LITERATURE DESCARTES DICKENS CONRAD GUTENBERG SHAKESPEARE KING JAMES BIBLE PEPYS DEFOE GOETHE AUSTEN BRONTË ORWELL Figure i.1 A series of timelines showing when key events in the history of physics took place
15. Zero A big idea about learning This idea is Cognitive Load Theory (CLT), which has been slowly gaining recognition since it was first developed by John Sweller in the 1980s. I have used the theory throughout this book to recommend activities and strategies and to explain why they work. CLT is not a theory-of-everything, but it helps explain how we learn to solve problems. CLT emphasises two types of memory: working memory and long-term memory, how they interact with each other and the external environment, as shown in Figure 0.1. whiteboard textbook notes teacher Working memory partner ¼ and many more. The external environment Long-term memory Figure 0.1 A model illustrating the external environment, working memory and long-term memory Working memory When we solve a problem, we store relevant, temporary information in our working memories. It is our mental workbench. Typical information manipulated in our working memories includes:
16. 4 A big idea about learning •• data to solve the task; •• information about the task; •• relevant processes and strategies; •• information about social interactions (I use group-learning a lot in my classes). The first important thing for teachers to know is that working memory is easily overloaded when dealing with novel information. Keeping track of three ideas is usually too much. If you are asking students to carry out a novel task, collaborating with new people using knowledge they haven’t memorised, and hope that they will be able to reflect on their learning at the same time, you may be out of working memory and out of luck. The second thing to know is that solving a problem at the limit of her ability does not allow a student to reflect on the process - a vital part of learning. So, even if the learner gets the problem right, you may have wasted learning time. Long-term memory The reason that some of us are better at solving problems than others is mainly due to long-term memory. If you have two capable students solving a problem, the one with the most relevant knowledge in her long-term memory is more likely to be successful. Relevant knowledge includes: •• subject knowledge – facts and the relationships between facts. •• learning knowledge – how to access the knowledge we need to solve a problem. •• general knowledge – the information we assume others know. This is important for effec- tive communication, especially when examples or questions are set within a context; for example, an examiner, textbook writer or teacher may assume the student knows about Africa, audio cassettes, the Tudors or snow. •• social knowledge – understanding the relationships, roles, rules and expectations of those around us. Social knowledge is key to solving problems in the real world. We store our long-term memories as schemata – networks of knowledge organised in mean- ingful ways. To become better problem solvers, students need richer schemata with more knowledge, connected more meaningfully. For example, a student with a well-developed schema about pressure will know the effects of pressure on: living things; elephant feet, high-heeled shoes, snow-shoes and drawing pins; submarines and high-altitude balloons; the bends; early vacuum pumps and the Magdeburg hemispheres; the gas laws (Boyle’s, Gay- Lussac’s and Charles’) and their history; Boltzmann and the kinetic theory of gases; Brownian motion; and a bunch of equations involving pressure. External environment Our working memories can only take in a small amount of information from the external environment at one time, which then rapidly fades. This is important for teachers because we influence our students’ external environment: the whiteboard, a demonstration, a worksheet,
17. A big idea about learning 5 the classroom display, the seating plan. The aim is to focus attention on relevant information and reduce distractions. Learners also influence their external environments. When a task gets tricky and working memory gets strained, effective learners use their external environment to reduce the load on their working memories. That’s why we count on fingers, do calculations on the backs of envelopes and work with others (making use of their working memories too). Every photo of a physicist shows a blackboard full of indecipherable, chalky marks – the classic useful external environment. Marking-up texts and diagrams, making notes, answering questions neatly and working effectively with peers are important strategies for learning. How can we use Cognitive Load Theory to accelerate learning? The first lesson from CLT is that students who know more, who have better developed sche- mata, are better at solving problems. If your primary goal as a physics teacher is to teach your students to be better problems solvers, your primary strategy has to be teaching your students more knowledge. The second lesson is that reducing Cognitive Load makes learning more effective. When you reduce the Cognitive Load, learners solve problems more effectively and learn more. Reducing Cognitive Load means stripping out all of the extraneous, confusing detail and dis- tractions from the task – especially for novices. Decide what you want your students to learn from a task and simplify everything else. When students learn, they are developing schemata – the knowledge and organisation of knowledge in long-term memory. Our main job as teachers is to boost students’ schemata. This means thinking hard about what we want our students to be able to recall instantly and with little effort – in other words: knowledge. Sweller’s research since the 1980s has shown that decreasing Cognitive Load increases learning. Researchers have found many effective strategies for reducing Cognitive Load to improve learning. I have described four strategies below: worked examples, completion prob- lems, the goal-free strategy and reducing the split-attention effect. Worked examples and completion problems The problem with problem solving is that you need to be pretty knowledgeable before you become good at it. We tend to teach new information and then immediately put it into a prob- lem. This doesn’t help most learners. CLT researchers have shown that an effective way to teach problem solving is by using worked examples. When a teacher models how to solve a problem, she is giving the guid- ance that novice physicists need. It is a way in: she makes the hidden process of solving the problem visible.
18. 6 A big idea about learning A worked example A ball bearing falls through oil. The arrows in Figure 0.2 represent the forces acting on the ball. Explain, in terms of forces, why the ball reaches a terminal velocity. Drag Weight Figure 0.2 The forces on a sphere in a tube of viscous liquid Model answer Imagine you are standing at the board – ideally the question is projected adjacent to where you are explaining and making notes for the class: 1 The weight of the ball is independent of the ball’s velocity – it doesn’t change. 2 The drag on the ball increases as the ball accelerates (the drag more than doubles every time the velocity doubles). 3 The ball stops accelerating when the drag matches the weight – it has reached termi- nal velocity. Try this several times with different contexts: a mouse falling down a well, a teacher jumping from a balloon, a small meteorite falling from space. Same concept, different context. But then what? The jump from seeing someone do it to being able to do it yourself is still big and working memory is quickly overloaded. One method is to give learners partially completed problems – this method is called prob- lem completion. You reduce the cognitive load, allowing the learner to focus her working memory on fewer aspects of the problem.
19. A big idea about learning 7 Completion problems Going straight from worked example to whole questions is very challenging for most learn- ers. Completion problems are half-completed answers which focus the learner’s attention on one element of solving the problem. The example below focuses a learner’s attention on putting the correct values into an equation. A 5kg ball rolls down a slope which is 2m higher at the top than at the bottom. How much more energy is in the ball’s gravitational store at the top of the slope than at the bottom? m = h = g = 10m/s2 Eg = mgh = = J As a student masters each element of the problem, the support should be reduced. For written answers, sentence starters reduce the cognitive load: On 14 October 2012, Felix Baumgartner created a new world record when he jumped from a stationary balloon at a height of 39km above the Earth’s surface. 42s after jumping, he reached a terminal velocity of 373m/s. Explain in terms of weight and drag how terminal velocity is reached. 1 The weight . 2 The drag . 3 When the drag has increased . One completion problem will not be enough. You will need lots. There are plenty of full ques- tions available in past exam papers or you can make up your own. Your job is to take a full question and partially model the answer, leaving only the stages you want your students to practice. For example: When his balloon experiment began to go wrong, Mr Rogers knew he had to jump. He was 5km high. Explain in terms of weight and drag why he reached terminal velocity as he fell. I have written sentence starters so that the learner does not have to sequence the answer for herself. Her task is to practice the individual stages of the answer. 1 His weight . 2 The drag . 3 When the drag has increased . Completion problems are an effective method for focusing attention on specific elements of a problem. They reduce Cognitive Load by zooming in.
20. 8 A big idea about learning Another method of reducing Cognitive Load is to remove the question all together. This method is known as goal-free. Reducing Cognitive Load by going goal-free This strategy appears counter-intuitive, until you think about what you really want your stu- dents to learn. Figure 0.3 is a good example. Figure 0.3 A typical moments question When you use this question in class, which of the following learning goals is most important to you: A: learning how to solve this type of problem B: finding out how much vertical force the support really supplies. I’m assuming you chose A (like so many of the questions we set in physics classes, we don’t really care about the answer to the question). Reducing the Cognitive Load allows the learner to learn. In the question above, simply cut out the text. You then have a situation to explore with your students – the plank on the support, as shown in Figure 0.4. Figure 0.4 A typical moments question with the question text removed
21. A big idea about learning 9 I use a cooperative strategy at this stage, asking students to discuss the situation in pairs. This strategy is called think-pair-share. Each student has a copy of the diagram and makes as many annotations as they can in one minute. Then, for one minute they compare their annotations with a partner. While they are doing this, I walk around the class and choose two or three students to contribute particularly useful ideas to the whole class. A considerable amount of learning has happened by this stage. They have practised retrieval, reinforcing their existing knowledge, and added to their weights-on-beams schema. Your students may now be ready to tackle the problem. You may wish to demonstrate the worked example yourself or set a partially completed problem. Going goal-free might sound directionless, but it is a powerful strategy for learning what can and cannot be done when faced with these given variables, leading to better problem solving. Reducing the split-attention effect to reduce Cognitive Load This strategy is about text and diagrams. When we have to split our attention between visuals and text, the Cognitive Load increases. How can you integrate the text into the question to reduce Cognitive Load? Because the text is separate from the diagram, and quite wordy, the learner’s attention is split, adding to the Cognitive Load for Figure 0.5. This reduces the students’ ability to learn from the experience. Figure 0.5 A typical moments question demonstrating the split attention effect In Figure 0.6, I have adapted the question to minimise the split-attention effect. This leaves more working memory available for processing. Embedding the text in the image does more than reduce Cognitive Load; it uses a strategy with shown learning benefits called dual- coding (see Sumeracki and Weinstein (n.d.) (http://www.learningscientists.org/dual-coding/).
22. 10 A big idea about learning Figure 0.6 A typical moments question adapted to reduce the split attention effect In all of these strategies, the aim is to reduce this support until your students can solve the problems on their own. In fact, when you continue to support for too long, Cognitive Load begins to increase again as the learner works around the support – this is called the expertise-reversal effect. When Twitter arguments erupt over knowledge-based curricula in history or the canon in English literature, physicists scratch their heads. There is very little disagreement over what knowledge is important in the physics curriculum. There may be a disagreement over when to teach certain topics or which types of renewable energy to include, but the key ideas are well established. Textbooks from the 17th century are recognisable today (and, more impor- tantly, so are the problems solved). To identify the knowledge, use the course syllabus, textbooks and other trusted sources such as the Institute of Physics’ TalkPhysics (2016) and Supporting Physics Teaching (talk- physics.org and supportingphysicsteaching.net). We can call this core knowledge. But, there is other knowledge that is often missed: •• What are the archetypal questions for this topic and how do I solve them? •• What are the relevant models and how do I know when to use them? •• What are the stories behind these ideas? •• What are the common misconceptions for this topic and how can I avoid them? In the following sections I have written about these additional types of knowledge. Archetypal questions Every topic in physics has its archetypal questions – the problems that are asked, in one form or another, in every physics exam. These problems are a common language for physicists – they are in every physics textbook around the world. They may be disguised using different contexts, but the deep structure and the method of solving it are the same. The key to mastering each problem is to do it so many times in different guises that the learner can spot it without thinking about it. Recognising the archetype becomes intuitive.
23. A big idea about learning 11 Model-based problem solving Physicists not only have heads full of problems and their solutions, they also have heads full of models and how to apply each one. For example, a physicist has several electricity models, each with different uses and limitations. She will use a simple current model for series and parallel problems, a model involving a beam of electrons for cathode ray tubes and a model of ions in a solution for electrolysis. Some of her models will be purely mathematical while others will be largely concrete. The physicist needs to know each model and the problems they can help solve. Each of the big ideas in this book have their own models. I have described relevant ones in each chapter and shown problems they can solve. The privileged status of stories – Willingham Back in 2004, Daniel T Willingham wrote an article about the power of stories in our brains. (see Willingham (2004) (https://www.aft.org/periodical/american-educator/summer-2004/ ask-cognitive-scientist)) He said stories are somehow easier to understand and easier to remember and are therefore “psychologically privileged” (Willingham 2004). Willingham identifies four Cs to help think about effective use of stories: causality, con- flict, complications and character. Physics stories are full of causality, and sometimes char- acter, but we often fail to emphasise the conflict and complications, possibly because they might distract. I try to put as much conflict and complication in as I can because that’s what makes the story memorable. The history of physics is full of relevant conflict (for example, Galvani and Volta or Benjamin Franklin and the Abbé Nollet disagreeing about the nature of electricity). And there is conflict that is purely about spite (for example, Isaac Newton and Stephen Grey). If conflict is memorable (and we are in the business of develop- ing memories), we should emphasise conflict wherever we can. And the history of physics is full of it. Just telling the story is powerful, but it is more powerful (and accountable) to have the students write sentences about the story during or after telling it. For example: •• In this story, causes . •• The conflict in this story is . •• The main complication in this story is . •• The main character is , who . In each of the physics chapters in this book, I have written key stories in the development of the idea. I have chosen each story with the four Cs in mind. My aim is to use the privileged power of stories to rapidly build and develop schemata. Misconceptions – When knowledge is wrong Babies are born knowing physics. They express surprise when objects appear to be sus- pended in mid-air or pass through walls. These are the primitive physics schemata we are all born with. Onto these we add experiences from our lives: metals are cold, batteries run out
24. 12 A big idea about learning of charge, the sun moves. Then in physics lessons we try to supplant this knowledge with a more formalised knowledge, often with mixed results. All of our children come to class with heads full of unhelpful knowledge – misconceptions. These were a huge area of PhD research in the 1980s and 1990s, and as such we know a lot about them. With the current emphasis on knowledge, the research into misconceptions becomes very relevant. One of my favourite books is Children’s Ideas in Science, edited by Driver, Guesne and Tiberghien (you may be able to get a copy second hand). It explores the world of novice scientists’ minds, rich with rational, plausible but incorrect knowledge. More recently, Harvard’s (2011) MOSART project has provided resources for teachers to identify misconceptions (it is useful for teachers to try too). You have to go through a short training process before being allowed access to the assessments. The questions are multiple choice – not for summative assessment, but to help teachers identify which of your students hold common misconceptions. Below is an example: Scientists say a metal doorknob indoors often feels cold to you because: 1 Cold from the doorknob goes into your hand 2 Heat from your hand goes into the doorknob 3 Cold moves from the doorknob to your hand 4 Heat is pulled from the doorknob by your hand 5 Metals are always colder than air. (MOSART 2011 test question) The marking scheme tells you the percentage of students who chose the incorrect answer (A) and what the misconception is. Recent evidence shows that our misconceptions never go away, but that we learn to select the relevant, acceptable knowledge for the situation. In other words, we all really believe that the Earth is flat and that Australia is impossible, but choose a different model in most situa- tions. An incorrect answer may not mean the student doesn’t have the knowledge – she may simply not realise she’s supposed to use it for this question. Physicists often cannot tell you how they identify the appropriate knowledge, model or technique to solve a problem. It is intuition. Nobel laureate Herbert Simon wrote about intui- tion: “The situation has provided a cue; this cue has given the expert access to informa- tion stored in memory, and the information provides the answer. Intuition is nothing more and nothing less than recognition” (Simon 1992). Intuition is recognition, and recognition is memory. This is why you need to practice as many questions as possible. Refutation texts Misconceptions are tenacious and resilient. When you think you’ve got rid of one, it reap- pears. Long-term memories are for life. Instead of trying to remove the misconception, the
25. A big idea about learning 13 solution is to recognise the misconception and build the acceptable understanding onto it. A strategy called refutation texts has been shown to work for this. A refutation text is a short paragraph, written by the learner, which does three things: 1 States the misconception; 2 Explicitly says that this is not correct; 3 States the accepted scientific viewpoint. I use sentence starters to reduce Cognitive Load, for example: Many people believe . However, . Most scientists state that . Using the MOSART example test question, an example refutation text is: Many people believe that when you touch a metal doorknob, coldness moves from the metal into your hand. However, cold does not move. Scientists say that it is heat moving from your hand into the metal that makes it feel cold. You will likely need to do this several times for each misconception using slightly different examples. It is worth spending time addressing misconceptions, because they will always come back, especially under stressful circumstances. Practical work in physics Science without practical is like swimming without water. (SCORE 2008: 10) Do you agree with this statement? Do your colleagues? Do your students? There is evidence that practical work is not an effective way of teaching content (see the Further Reading sec- tion at the end of this chapter), but it is given a high status in UK classrooms. Using practical work is a choice – there are usually other ways of teaching whatever you are planning to teach, techniques that take less time and use fewer resources. If you can teach more efficiently using a more direct model of teaching, perhaps you should. But if you decide to use practical activities in your lessons, you need to make it count. Reducing Cognitive Load for practical work Cognitive Load Theory explains why students don’t learn well from practical lessons: there is too much happening at once. Learners have to: collect and assemble apparatus, follow instructions from memory or from verbal or written instructions, work collaboratively, make and record careful observations and then pack everything away. And that list does not include thinking about the science.
26. 14 A big idea about learning So how can you reduce the Cognitive Load? The simplest way to reduce Cognitive Load is for you to do the practical as a demonstration. While you are modelling the experiment, you can direct their attention to relevant details. If you want them to do the practical work themselves, remove as much Cognitive Load as possible. What is it exactly that you want them to learn or practise? Do they need to assemble the practical themselves? Do they need to draw the results table or graph axes? Is it worth training them to get the equipment out and put it away so that it becomes automatic? Literacy – A different sort of physics problem What are the Cognitive Loads associated with reading and how can we reduce them? Reading is a physics problem that doesn’t receive much attention in class. I think it should. Science professionals read a lot (see Figure 0.7). Time that science and engineering professionals spend reading per week 13.27% 15.3% 20+ hours 6.12% 15−19 hours 10−14 hours 18.4% 5−9 hours 46.9% 0−4 hours Figure 0.7 Reading lessons for scientists, from Ben Rogers September 2015. https://eic.rsc.org/ analysis/reading-lessons-for-scientists/2010065.article And they read to learn (see Figure 0.8). Why do scientists and engineers read? 80 60 40 20 0 for for to keep for information understanding up-to-date interest Figure 0.8 R eading lessons for scientists, from Ben Rogers September 2015. https://eic.rsc.org/ analysis/reading-lessons-for-scientists/2010065.article
27. A big idea about learning 15 The problem is, most science, technology, engineering and maths professionals taught themselves (see Figure 0.9). Who teaches scientists and engineers how to read professional texts? 80 60 40 20 0 Taught myself Taught at Taught at school university/ college Figure 0.9 Reading lessons for scientists, from Ben Rogers September 2015. https://eic.rsc.org/ analysis/reading-lessons-for-scientists/2010065.article Teaching yourself is fine, as long as there is support there when you need it. In my expe- rience, there is little support and many fall through the net, dropping physics at GCSE or A-level because they can’t access the texts. They misread exam questions, they find text- books inaccessible and scientific papers opaque. CLT explains why reading is difficult and suggests how to make it easier. It is difficult because all three memories are in use: long-term, working memory and external memory (the text and any scribbles added to it). The two most important things to improve reading are in your long-term memory – or they need to be. They are vocabulary and knowledge. Vocabulary for reading Science teachers are excellent at teaching science vocabulary. We explain clearly, we use example sentences, we revisit, we match words to diagrams. We use every trick we know. But we ignore key non-specialist vocabulary. Words like: determine, suggest, establish and system (I took these from a couple of recent GCSE papers). These words should be taken as seriously by science teachers as technical vocabulary. Knowledge for reading Along with vocabulary, the most important part of understanding is the stuff you already know: your schemata. As we read, the information in the text is held in your working memory to be presented to knowledge from your long-term memory, like a debutante or a novice
28. 16 A big idea about learning speed-dater. If sense can be made, fine, but learning takes place when the long-term memory is modified, added to or contradicted. Skills for reading comprehension It isn’t worth spending too long on generic comprehension skills. Research evidence shows that there are a few simple strategies which help, but these can be taught quickly and effec- tively over a few weeks. After that, you will see little improvement (see Daniel T. WiIlingham’s (2006) article ‘The Usefulness of Brief Instruction in Reading Comprehension Strategies’ In class, I focus on the following skills – or habits – that expert science readers (people like us) use most often. To do this, I usually put students into groups of four and give them a reading card each. The student with card one reads a paragraph and then each student takes turns to finish the sentence starter on their card. Sentence starters can include: 1 I Wonder… Expert readers ask questions of the text. Often these questions are related to meaning, but they can be “I wonder what that word means?” or “I wonder why the writer said that”. 2 In other words… Paraphrasing (rewording, often making clearer) is a powerful compre- hension checking skill/habit. 3 I predict… Asking readers to predict what comes next in a text is a useful way of drawing attention to the structure and conventions of scientific texts. It is extremely useful when scanning a text for the information you want to be able to predict whether the informa- tion might be in a nearby section. 4 So far… Summarising is a habit which encourages prioritisation of information. When the fourth student has finished, they each pass their card to the team member on their left and repeat the process. If these activities can be practised enough (several times over a few weeks, with occa- sional top-ups) they quickly become part of a learner’s reading schema – a low effort strategy to use when reading. What are the Cognitive Loads of writing and how can we reduce them? We can only think about two or three novel items at one time, so writing is hard. There is a lot to think about. Table 0.1 shows two things: 1 Why writing is a high-load activity. 2 How to reduce load for novice writers.
29. A big idea about learning 17 Table 0.1 Strategies for reducing Cognitive Load associated with writing Cognitive Load Reduce the load for novices by using… 1 Choosing the relevant knowledge Mind map/notes. and vocabulary. 2 Planning the overall structure of the Outline plans/sequencing activities (e.g. print out the text – the argument. individual ideas for students to sequence). 3 Planning short sequences – a couple Bullet points/sentence sequencing activities. of sentences to make a point. 4 Structuring individual sentences. Sentence starters/write–rewrite activities. 5 Spelling, punctuation and grammar. Teach model sentences/remind students how to punctuate / practise punctuating sentences correctly. All of the Cognitive Load activities are important; practice them one at a time. Decide which part of writing you want your students to develop and reduce the Cognitive Load from the other elements. The following writing task is an analysis of the Cognitive Load imposed by a typical physics writing task. Writing task: Explain why a skydiver reaches terminal velocity. What is the knowledge required by this question? 1 Key knowledge: a Gravity b Air resistance c Velocity increases d Resultant force decreases e Balanced forces f Terminal velocity. 2 Outline: a At first – no motion b Speed increases c Until terminal velocity. 3 Sequence of sentences: a v = 0, acceleration due to gravity. No air resistance. b v increases → air resistance increases → resultant force decreases → accelera- tion decreases. c v = forces balance → acceleration = 0 → terminal velocity.
30. 18 A big idea about learning 4 Key sentences: a Initially, the velocity is zero, so the air resistance is zero and the skydiver accelerates. b As the velocity increases so does the air resistance, resulting in a decreased acceleration. c When the air resistance balances the force due to gravity, the acceleration reaches zero – this is the skydiver’s terminal velocity. 5 Spelling and grammar (SpaG) check. 6 Proofread and edit. How to teach writing in physics Writing is one of the best ways to ensure your students are thinking, and to get an insight into their thoughts. But because writing has a very high Cognitive Load, it is worth separating each element of writing out: work on one element at a time and assess one element at a time. These elements include: identifying relevant concepts, arranging these concepts in a logical sequence, constructing well-formed sentences and structuring the writing. CLT has revealed several useful techniques to make learning through writing more effective: 1 Start with model answers. Greg Ashman (2017) recommends modelling followed by near identical problems for students to complete (gregashman.wordpress.com/2017/05/13/ four-ways-cognitive-load-has-changed-my-teaching/). 2 Use completion problems. Choose which type of Cognitive Load in Table 0.1 (see page 17) you want your students to focus on and reduce the rest. 3 Use gap fills, sentence starters and mind maps as effective techniques to reduce Cognitive Load. Later you will want to demonstrate combining the different elements into a coherent piece of writing. 4 Write–rewrite. This Reading Reconsidered technique (Lemov et. al. 2016) is especially effective in reducing Cognitive Load when writing complex scientific sentences. Students write their sentence once, share effective answers and then rewrite. Your students are effectively unloading Cognitive Load as the first draft, allowing greater intellectual resources to be applied to the second draft. 5 Reduce support. As the student develops expertise, these strategies eventually increase Cognitive Load as they get in the way. Learning physics means learning to solve the problems of physics. Cognitive Load Theory provides a model and strategies to make learning to solve the problems of physics more The five remaining chapters apply Cognitive Load Theory to five big ideas of physics: electricity, forces at a distance, energy, particles and the universe, always starting with the stories.
31. A big idea about learning 19 Further reading – A big idea about learning •• Bringing Words to Life, Beck, McKeown and Kukan, The Guilford Press. 2002 •• Children’s Ideas in Science, Driver, Guesne and Tiberghien, Open University Press, 1985. •• Cognitive Load Theory: Research that Teachers Really Need to Understand, Centre for Education Statistics and Evaluation, www.cese.nsw.gov.au/images/stories/PDF/ cognitive_load_theory_report_AA1.pdf. •• Feynman’s Tips on Physics, Basic Books, 2013. •• MOSART (Misconceptions-Oriented Standards-Based Assessment Resources for Teachers) www.cfa.harvard.edu/smgphp/mosart/ •• Practical Work for Learning, The Nuffield Foundation, www.nuffieldfoundation. org/practical-work-learning. •• Practical Work in Science: Misunderstood and Badly Used? Jonathan Osborne, SSR, September 2015. •• Practical Work: Making It More Effective, Robin Millar and Ian Abrahams, SSR, September 2009, www.gettingpractical.org.uk/documents/RobinSSR.pdf. •• Reading Lessons for Scientists, Ben Rogers, September 2015, https://eic.rsc.org/ analysis/reading-lessons-for-scientists/2010065.article. •• Reading Reconsidered, Lemov, Driggs and Woolway, Jossey-Bass, 2016. •• The Association for Science Education (ASE) published two editions of their jour- nal School Science Review (SSR) on practical work in June and September 2015. ASE members can download the papers from the website at https://www.ase.org. uk/journals/school-science-review/. •• The Learning Scientists, Six Strategies for Effective Learning: Materials for Teach ers and Students, www.learningscientists.org/downloadable-materials/. •• The Reading Mind, Willingham, Jossey-Bass, 2017. •• The Writing Revolution, Hochman and Wexler, Jossey-Bass, 2017. •• Thinking, Fast and Slow, Kahneman, Penguin, 2011. •• Why Minimal Guidance During Instruction Does Not Work: An Analysis of the Failure of Constructivist, Discovery, Problem-Based, Experiential, and Inquiry-Based Teach ing.’ Kirschner, Sweller and Clark. www.cogtech.usc.edu/publications/kirschner_ Sweller_Clark.pdf.
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