The Day Job

I have a full-time job, although ironically I’m not managing to blog nearly as much as when I was a classroom teacher, which was noticeably more than full-time. I’m fielding a lot of queries about physics teaching concerns on Twitter, which is fine, but I thought it might save me a lot of hassle if I put the same links here. Over a third of those teaching physics topics, according to data reported on p2 of this report from Wellcome, are not physics specialists. This matches the data I’ve seen through my day job at the Institute of Physics.

But before I say too much, let’s start with a disclaimer: what’s on my blog and on twitter from me is not official IOP policy or approved content. The IOP doesn’t care about the music I listen to, the political views I share, the arguments I have about gun control, mental health support or how to spell sulphur. (Well, maybe that last bit.) When I blog and tweet, I speak for myself. I’ll do my best to explain the IOP approach, for example with energy stores and pathways or the best way to support gender balance, but my bosses will only care about what I send from my work email account on work time. They’ll defend me on that – or not, as the case may be – but my off-duty self is not their problem.

Teacher support via the IOP

Whether you’re new to teaching Physics or have been heading your department for decades, the IOP has supporting material for you via the For Teachers page. Among other suggestions, this links to the TalkPhysics forum (free to join), which I recommend for queries that include more detail than the average tweet. There are several projects running to support schools, including the Stimulating Physics Network and Future Physics Leaders; these run alongside the locally-based Physics Network Co-ordinators. If you want your department to receive a little more support, you can join the schools and colleges affiliation scheme which gets you the journal Physics Education among other perks.

Detailed and in-depth discussion of pedagogy is broken down into 5-11, 11-14 and 14-16 topics on the Supporting Physics Teaching site. If you’re after something specific you may want to drop me a line on Twitter, but the content is evidence-informed and referenced. Great material for when you have a little time to think and plan.

The Improving Gender Balance project grew out of the Girls in Physics report. Lots of resources are available and my colleagues are always happy to talk to schools interested in applying these ideas. The last set of data showed that in around half of UK state schools not a single girl carries on to A-level physics; the imbalance in some subjects is even worse.

For hands-on advice the IOP supports the Practical Physics site. This grew out of the Getting Practical materials and is well worth exploring, with guides to pass on to technicians. You may also find the Teaching Advanced Physics (TAP) site useful, not least because some of the concepts are now covered in the GCSE curriculum as well as A-level.

If you’re an established physics teacher, the chances are that you do some informal coaching of colleagues even if you don’t have an official role. This is what my day job is all about, so please give me a shout so I can steal your ideas discuss the sharing of good practice. You may also be interested in Membership and applying to be recognised as a Chartered Physicist, and I have supporting materials that could help.

Other sources

I may be biased but I think the IOP materials are a good start. There are, of course, other places to look! I’ve been involved with a couple of these but others I know from using them with students or colleagues.

There are simulations available at PhET and the Physics Classroom. Understandably they take an American approach at times, but they’re well worth checking out. Double check suitability before setting for homework, as some will need Java installing or updating so may not play well on mobile devices. Both include pedagogy discussions for teachers as well as simulations for students.

STEM Learning – what I still think of as the eLibrary, and linked to the physical library at York – has loads of great resources, including versions of some of those linked above. Two collections in particular may be of interest, which organise the resources according to a curriculum: 14-16 science resource packages and A-level science resource packages. Bizarrely, the topics within each subject are alphabetical rather than logical, but that’s pretty much my only criticism. A free sign-in is required.

I do some freelance work with Hodder Education. The textbooks are obviously worth a look, but I’m not here to advertise. One project you can get for free is the Physics Teacher Guide. This is matched to the student textbook and online (subscription) resources, but may be useful even if you don’t have the budget to get for your workplace.

As an ASE member, I get the journal and magazine regularly. You shouldn’t need a login to access the Physics resources, which are an eclectic collection. I highly recommend the free downloads from the Language of Maths in Science project. Heads of Department might find membership worthwhile simply to access the Science Leaders’ Hub.

For Students

You may already pass these on to students – or have opinions about why that is a bad idea – but I think SchoolPhysics (from the author of the Resourceful Physics Teacher), HyperPhysics (concept maps linking physics ideas, probably best for A-level) and Physics and Maths Tutor (for past paper) are worth a look. Several of the above links, of course, may also be useful for them too.

A-level students can get a free e-newsletter, Qubit from the IOP. Hodder also publish Physics Review for A-level students, which is a good way to extend their learning beyond the curriculum.

EDIT: I was prompted about IsaacPhysics, which of course is a great site and one I recommend to colleagues. Questions are organised by linked topics for the spaced retrieval practice we all know is so important. Thanks to @MrCochain for the reminder. They also have funded places for a residential bootcamp this summer for students in England between years 12 and 13 who meet one or more criteria eg in first generation going to uni.

Please share any broadly useful resources via the comments; I’ve deliberately not started listing teacher blogs because I’d be here for ages. Maybe that can be a later post? But I have several others on my list, including materials to support the learning of equations and a review of an old science textbook. There’s never enough time…

 

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Equation recall test

This was supposed to be a really quick job. For something I’m working on, I was looking at the equations students need to recall for the GCSE Physics exam (specifically AQA). And it annoyed me that they weren’t in a useful order, or a useful format for testing. So I’ve made a testing sheet, with pages for Energy, ‘mostly Electricity’ and Forces.

There are four columns, which are blank in the first three pages (for students) but completed in the answer sheet version. Because I’m good to you.

Download eqn testing sheets as PDF

Equation for…

I’ve given the word, not the symbol – thoughts? (Could/should that be another column?) I’ve removed a couple of what I see as duplications, and missed out momentum because I was thinking of this as for everybody. Plus it would have mean adding another row and I was sick of messing with formatting.

Which variables are involved?

For students to write in the variables in words, as a starting point. The idea would be that you can give partial credit for them getting part way there, because we should recognise the early stages of recall. You may off course have them skip this bit later on.

What are the symbols?

If they know the variables, can they write down what they will look like in the equation? This would be the other place for them to show they know what the ‘equation for…’ variable could feature in symbol form.

Equation

Formatted as best I can, in a hurry in Publisher. I’ve used the letters as listed on the formula sheet, p95 of the specification. Even when I disagree.

As ever, please let me know if/when you spot mistakes. Because it’s in Publisher I can’t upload the editable version here, but drop me a line in the comments if useful and I’ll send it your way.

Review: 30 Second Physics

It’s always useful to have a few popular science books available for interested students. These make great summer extension work for some, and even less enthusiastic pupils may dip in and out of good prose. Adding magazines and a selection of science blogs is always worthwhile, of course…

30 Second Physics, Brian Clegg (ed)

Ivy Press, 2017, 160pp, £9.99, ISBN 9781782405146: buy via Amazon.

30-Second Physics cover
30-Second Physics

The book follows an established format; each edited by an expert in the field, and broken down into topics with small sections. In some ways it is the ultimate expression of a textbook with a double-page spread for each idea! It is, however, much briefer in detail but wider in scope. It’s worth noting that each topic is illustrated with a full-page picture, many of which owe more to artistic design principles than scientific diagrams. This is sometimes a missed opportunity.

Most of the text would be accessible to able GCSE science students and above; any who find particular ideas challenging can refer to the ‘three-second thrash’ on each page. If more detail is needed, there is a hint to further study, page references to related topics and brief biographies of relevant scientists. Each of the six sections includes one longer description; the usual physics suspects appear.

I’m not sure if the would supply useful extension work for specific topics but could be a good way to encourage students to consider links to the ‘Big Picture’. Because the text is accessible, selected bits would also work well to challenge able students at the upper end of KS3. Depending on personal preference, it could also be loaned out to students who might prefer to dip into something briefly rather than digging into something meatier.

One cautionary note; the pages on Energy are, unsurprisingly, aligned with the ‘types and transformations’ model rather than ‘stores and pathways’. This would not even be noticed by most parents, but students may find the reversion to a model no longer recommended for school teaching is confusing. The physics, of course, is fine – it is just the way the equations and processes are described in words that may cause difficulties. And as a physicist, I think the lack of equations on the pages is a shame; I suspect the average reader would consider it a benefit!

Overall, I’d recommend this as a good starting point for a classroom bookshelf but most interested students will soon move on to books on more specific physics topics. It would be a great for interested parents so they have a clue about what their children are encountering in lessons.

I was sent a free pre-publication copy to review; it was released on Amazon on 17th August.

#ASEslowchat Tuesday: Practicals


I can’t comment on what is happening in my classroom, or my department. Because I don’t have a classroom; instead I work with teachers in their classrooms, supporting their departments. So most of what I’ll be sharing will be at one step removed, but it is based on what ‘real’ teachers have told me is happening in their schools. I’ve played around with the stimulus questions a little.
Which required practicals have you completed with your classes; have you only completed these, or gone beyond them? Why?

I posted a little while back about how I felt the required practicals should fit into a balanced science curriculum. (This was a different post to one from even earlier, based o a draft of the AQA required pracs.) Nothing I’ve seen has caused me to change my mind. The summary is that whether a practical is required or not it should be used in the same way; to support teaching of science content and skills. It might, of course, be worth returning to the required practicals as part of the organised review/revision schedule, because they’re effectively content. Until then, ask the same questions, practise the same skills, as you would for any practical. (And, of course, don’t neglect these aspects if a practical is ‘unrequired’!)

Has the GCSE impacted on the work of the technicians in the department? Have you had any issues with equipment?

Not being in a school full-time, I’m not sure about the workload side of this. I don’t think it’s been a huge issue – certainly compared to lots of ISAs to worry about! (I hope school technicians are being encouraged to contribute to this topic, by the way.) But I have been doing a fair bit about the physics practicals with teachers, in school and by email, so I have a few resources to point to.

There is a dedicated TalkPhysics group for the GCSE required practicals – obviously just the physics ones. It’s fairly quiet at the moment, but I/we would love to see more teachers on there swapping ideas and answers, for example about specific components for I/V graphs or precise methods for using a ripple tank. If you’re not already a member, you can get a free login in a day or so, and the group is open to all. Technicians and all teachers of physics – not just physics specialists – are welcome. Please join in.

Most equipment issues I’ve heard about have been predictable:

  • Getting a class around a ripple tank is hard. Much of the work can be done in pairs by putting a piece of laminated squared paper in a Gratnells tray – other trays are available – adding a centimetre of water with a couple of drops of ink, then making and timing ripples. Very fast, very cheap, and lots of data to criticise.
  • Dataloggers for a=F/m. As you might expect, manufacturers are trying to log complete systems which will work brilliantly for a week then be a pain to set-up and calibrate. If you can use phones in school, kids can probably use slow-motion cameras to collect some useful data. Alternatively, I’m a huge fan (no commision, sadly) of the Bee Spi V lightgate. It displays either speed or acceleration of an object passing through it. It doesn’t log it, which to my mind is an advantage as it means kids have to do the table/points/line bit themselves. They’re £20 each, run on batteries and don’t need to be plugged into any device.
  • The specific heat capacity practical – assuming you have the kit – has always produced data with, shall we say, lots to comment on. An improved method is available from PracticalPhysics, and it’s easier if you can (a) use a joulemeter and (b)record the maximum temperature, not the temperature at the end of the heating time.

How are you developing knowledge of practical work and investigations in your teaching ready for the examinations? 

‘Required Practicals’ is one of the sessions I run in schools as part of my day job with the IOP. So allow me to invite you to a virtual session, which will require you to imagine all the hands-on sections. There are presenter notes with even more links than in the slides themselves. PNCs will often run their own versions of these, and we do a lot at days and events open to all teachers. Please consider this an invitation.

If in doubt, checking out the work of Ian Abrahams is always worthwhile. He’s got a book out with Michael Reiss fairly recently: Enhancing Learning with Effective Practical Science 11-16, which I will buy as soon as my next freelance cheque arrives. Unless anyone would like me to review it, hint hint. He writes regularly in SSR so you’ve probably experienced a flavour of his work already.

A few years ago, Demo: The Movie was unleashed on an unsuspecting world by @alomshaha and co. It should be required watching for all science teachers and departments, and provides some great ideas about how to make demonstrations much better for learning. He’s got loads of films, some of which aren’t directly relevant but the techniques discussed are great. I reflected on some of the material in a blog post too.

Other resources I’d recommend (there will undoubtedly be some overlap) are collated at STEM Learning (the eLibrary that was, once upon a time). And I always like to put in a word for the SchoolPhysics materials by Keith Gibb, author of the Resourceful Physics Teacher.

Something I’ve chatted about in workshops, on Twitter and elsewhere; you may find it useful to break down the POE approach in a slightly more specific way which I call PRODMEE:

  • Predict: what do you think will happen? (encourage specific changes to specific variables)
  • Reason: why do you think that? (from other science content, other subjects, life experience)
  • Observe: what actually happens? (we may need to ensure they’re looking the right way)
  • Describe: in words, what happened? (qualitative results)
  • Measure: in numbers, what happened? (quantitative results, devices, accuracy/precision, units)
  • Explain: what’s the pattern and does it match the prediction? (digging into the mechanism)
  • Extend: why does this matter? (other contexts, consequences for everyday life)

What resources or advice can you share with other teachers about approaching a specific required practical? What issues and opportunities have you come across when going about teaching the required practicals to your classes?

A few suggestions I’ve made in workshops, often based on conversations with teachers; this is obviously an incomplete list!

  • Density is boring; why not provide a few blobs of blue-tac and have kids plot mass against volume on a graph. Make it more challenging by hiding a ball bearing inside one to provide an anomaly to the line of best-fit. Or can students separate LEGO, Mega-Bloks etc based on density?
  • Hooke’s Law: as the kids have already seen it, why not try using strawberry laces? Alternatively, there’s a simple set-up using copper wire from PracticalPhysics. And you can always use it to hammer home the idea of science-specific vocab, because ‘elastic’ bands aren’t elastic.
  • Acceleration: I mentioned Bee Spi V for measuring earlier. My only other suggestion is to always teach it as F/m=a so you start with the cause (force), shared out because of the conditions (mass) which leads to a consequence (acceleration).
  • Ripples: discussed above, but you can also use a speaker as a vibration generator for some interesting results.
  • Heat capacity: An old experiment uses lead shot which falls a known distance and heats up. Like stroking a metal lump with a hammer, this is a nice example of the idea that the energy in a thermal store can increase without ‘heating’ as we might normally consider it.
  • I/V characteristics are a lot more interesting if students must compare results from a mystery component to standard graphs. This is included in the presentation of my workshop, linked above.
  • Resistance, series and parallel: instead of just reusing the old ISA hardware, why not try taking measurements of different versions of squishy circuits dough?

 

 

 

 

Energy Language Thoughts Part 4

Parts 1 (Introduction), 2 (Pathways/Processes) and 3 (Stores) are all available and will help make this more useful. Please continue to comment, on whichever post seems most relevant, if you’ve any queries or suggestions. Thanks to those who have already done so.

Practical Approaches

stores-or-pathways

The IOP guidance begins by taking snapshots before and after an event and describing the changes to various possible associated stores. The alternative is to think about the physical processes – which will be variably familiar to students, depending on age – and thinking about the effect they have on parts of the system. YMMV.

The famous energy circus can be used, but be cautious! Some make much clearer examples than others. In most cases you will need to be very specific about the start and end points you wish the students to consider. I recommend checking out the SPT guidance. In particular, the ‘one step at a time’ diagram shows why chains of energy can cause problems. The suggestion there, which I endorse, is that you:

  1. start with the idea of fuels ie chemical stores
  2. make clear that fuels limit effects, they don’t by themselves cause the effects
  3. give high, hot and stretched objects as equivalents, but as they’re clearly not fuels we associate them with
  4. gravitational, thermal and elastic stores respectively

Explained at SPT

I’d suggest looking at your energy circus for clear demonstrations of these to begin with. Next would come a kinetic store, probably as an endpoint. A gyroscope or Newton’s cradle is a nice example of a kinetic store which lasts long enough to be plausible.

Approaches to consider

You could have a first round to develop some basic ideas, then a second with more complex snapshots (either more than one store involved at the end, or the same kind of store but associated with different objects).

Have students identify just the stores to begin with, discuss them as a class, then come back and add descriptions for the processes. This could be split between lessons; that way you can provide correct stores in the second lesson and concentrate on processes. In some cases, such as the classic filament bulb, two similar pathways will be needed.

  • From: thermal store of filament
  • Via: heating by visible radiation, heating by IR radiation
  • To: thermal store of air in the room

If you want them, here are energy-circus-cards as pdf (includes example and blank cards)

Provide sets of laminated cards with stores, and arrows for the descriptions of processes. Labelled arrows are of course an option, but be aware of limitations and I’d include some blanks.

Again, cards-for-energy-v3 as pdf to save you a few minutes.

An extension could be to suggest measuring equipment and/or units for the relevant stores in each situation. If returning to these examples at GCSE, then recall of the equations are the natural next step.

Consider including actual photographs for some situations that cannot be easily reproduced in the lab; this would be a good way to introduce some examples from biology and chemistry. A food chain in biology might, for example, be described so:

  • From: chemical store of lettuce
  • To: chemical store of rabbit

Then

  • From: chemical store of rabbit
  • To: thermal store of rabbit, kinetic store of rabbit, chemical store of fox

And finally

  • From: thermal store of rabbit, kinetic store of rabbit
  • To: thermal store of air

For chemistry, exothermic reactions will involve heating by particles and/or heating by radiation pathways. If the material explodes (which in my experience is the preferred result) then there is some kind of mechanical working too, yes? Be prepared for questions about state changes; the best approach is that latent heat means the thermal store is not only identified by the temperature change. Which, yes, is a complication.

It’s probably worth adding notes – mental or otherwise – to the other science topics so you can remind students of the new language. If you have particular queries, drop me a line in the comments or, for a more considered answer, join in with the discussions on TalkPhysics.

This seems like a good chance to consider the Big Ideas in Science Education. Which should be up anyway, somewhere, but it’s always nice to have a reminder.

Exams and Textbooks

This is where I must admit defeat. I know – in fact I started the first post in this series with this point – that teachers want to know what will get marks and what won’t when it comes to the exams. Sadly, I don’t know. At least one board used the old language in the sample papers originally made available. The list of stores is not consistent between boards, though I hope that makes more sense after Part 3. And so on.

I’m sure we’ll all be happier once we see more examples of possible questions, but I’m not involved much with the boards so I have no insight. My advice – which isn’t official IOP guidance, nor is it specially informed – is that if your students can explain the mechanisms behind the transfers, they shouldn’t need to worry about the language, either pathways or processes. For the stores, it’s probably more important that they can identify the equations that are relevant and be able to do the maths – that, of course, hasn’t changed! I’ve recently discovered that Richard Boohan is putting together some materials; I shall be watching with interest.

Whether students will be penalised for talking about light energy, sound energy, electrical energy – that I don’t know. I also don’t know how much emphasis will be placed on this language by those marking biology and chemistry questions. So I’m not much good, really. Sorry!

Last appeal for comments, feedback, criticism… please let me know what you think of these four pieces. At well over 3000 words I appear to have accidentally written an essay. I hope that if you’ve waded through it, you feel it was worth your time. Please do give me a shout if there’s something I can do to improve the time spent vs time saved ratio.

Energy Language Thoughts Part 3

As you would expect, this follows on from Part 1 (Introduction and Summary) and Part 2 (Pathways/Processes). Even if you’ve read them, you might want to look back at the comments readers have made  – many thanks to everyone who has been able to take the time.

Descriptions vs Labels: Stores

The stores are not simply renamed ‘energy types’. A lot of them use similar words, but that’s because they’re trying to describe the same physics. They represent the changing properties of a part of the system, caused by it gaining or losing energy. When a steel block undergoes physical processes, it changes in a measurable way. It might change shape. Its temperature might change. It might be moved away from the Earth’s surface. It is a shame that exam boards are taking different approaches, but the eight suggested by the IOP are:

  • chemical store
  • thermal store
  • kinetic store
  • gravitational store
  • elastic store
  • nuclear store
  • vibration store
  • electric-magnetic store

More details at SPT

Like the processes, there are sometimes more than one way to consider what is happening. If a gas is heated, the change could be considered in terms of the measured temperature change (thermal store), or in the increased movement of the particles (kinetic store). Realistically, there are not many situations where two stores will seem equally appropriate. And when they are, this is actually a strength. The two approaches will give values for the energy change which are the same. Energy is energy, whether it is considered in the context of a thermal or kinetic store. The whole point of using energy as a ‘common currency’ is that is translates between contexts.

The stores, as discussed in my introductory post, are each a way of considering a physical measurement and an associated equation. The idea is that you consider the ‘before’ and after’ situations for relevant stores, as snapshots. (The exception, for school-age students at least, is a chemical store where the values are found empirically.) I produced, based on some ideas from IOP colleagues, some energy store ‘bookmarks’ which bring together the different aspects. They wouldn’t take long to put together, but you’re welcome to my version:

stores-bookmarks as pdf

Common Variations

The vibration store can be considered as a kinetic store which oscillates. The easier measurement is not speed but amplitude and time period. Imagine trying to find a meaningful value of the speed of a swinging pendulum, for example. But some boards are omitting it, which is fairly easy to justify.

I’m less happy that at least one exam board (AQA) miss out the nuclear store entirely. This seems like a huge mistake to me as it uses the one equation pretty much everyone knows from physics, E = mc2! It would also make it impossible to start with the sun, which makes most biology a bit tricky. (From nuclear store via particle heating processes to sun’s thermal store then via radiating processes to Earth’s thermal store and biomass chemical store)

The electric-magnetic store – not electromagnetic – is about the position of objects within two kinds of field. Now, I know they’re related – Maxwell’s equations and all that – but I think for most students it’s a lot easier to consider two separate stores, the magnetic and the electrostatic. The upside is that this means you can clearly link them to gravitational stores and so cover fields as a ‘meta-model’. The downside is that it makes the stores list look even more similar to the old approach. If you take this tack, make sure you emphasize that it’s an electrostatic store to clearly distinguish from the electric current pathway.

Which brings me to…

What about light/sound/electricity?

The SPT resources have some very good explanations on this. My reasoning is that they are processes which only have meaning if we think about duration. To describe them in numbers, we use power in Watts rather than energy in Joules. So they are, obviously, real physics effects. But they fit best into this model as processes shifting energy between stores, rather than stores themselves.

Disclosure: my issue with this is that a very strict interpreation of thi would seem to rule out kinetic stores as well. The snapshot approach – comparing the change to stores in between two static frames – makes it hard to reconcile a moving object with a single instant. Hmm. Although we have no problem with considering momentum at a moment in time, yes? Contrariwise, students may have an image of light as being made up of photons as moving objects, or when older the equation E=hf. Hmm again. And what about latent heat? This is best considered as a special term of the thermal store, but it’s not obvious. (Thanks to my colleague Lawrence Cattermole for reminding me of this today.) Of course, no model is perfect. The test is whether this approach is better than the ‘types’ of energy approach that has been so pervasive.

‘Better’, of course, is not a very scientific term! It is more accurate when describing the physical processes. The words are a closer narrative match to the equations students will need to use as they develop their physics. The model is different to what we and our students are used to, but objecting to it on that basis seems short-sighted. As I originally said, you could argue that the timing is unfortunate, with new specs and grading systems, but I don’t think we’d ever be at the point where all science teachers welcomed a change with open arms.

As always – please comment, respond, shout angrily at me using the field below.

Energy Language Thoughts Part 2

The previous post was a summary or introduction – thanks to all those who have commented already – and tomorrow I’ll be moving on to stores in more detail. But for now…

Descriptions vs Labels: Processes

To make life easier, humans like to use shorthand for complex processes. These are categories or labels, not detailed descriptions. Many pathways or processes can be put into one of these categories, but the aim should always be end up able to describe what is actually happening.

  • Heating by particles
  • Radiating (aka heating by radiation)
  • Electrical working
  • Mechanical working

Longer explanation at SPT

How we choose these categories will alter our interpretation. For example, are sound waves a form of mechanical working? Or do we include all waves in the ‘radiating’ category? The physics description of what is happening is what we and our students should be concentrating on, because it doesn’t change. The ideas about Johnstone’s Triangle that I’ve read about via Michael Seery’s blog, from chemistry education, has obvious parallels.

johnstones-triangle-1024x573

Reproduced from Michael’s post, credited to University of Iowa.

If we can link the macro (observations in lab) and sub-micro (particles and interactions) levels, the symbolic can wait. A similar discussion is had on SPT about alternating between the lived in world and a theoretical model.

Avoiding using these categories – which by their very nature are imprecise – might be worth considering. It would be very easy for students to think they have to assign any physics process to one of the four listed above, without really thinking through what’s happening. (If you’d like to consider symbolic approaches, I’d suggest checking out the physical versions of energy bar charts as described here by Greg Jacobs.)

As pointed out by several – most recently Richard Needham on Twitter – changing how energy is described in physics lessons means nothing if we can’t apply this to biology and chemistry. And it needs to make more sense there too! In school chemistry, heating and radiating (in the form of light-emitting) will be the significant processes. The equations used later on for enthalpy change – endo and exo-thermic reactions and so on – work nicely with this framework. In school biology, the transfer of energy is usually about photosynthesis (a radiating pathway fills a chemical store by the production of glucose/oxygen) or nutrition/metabolism. (More about stores in the next ‘chapter’.) One of my jobs is to have a closer look at the KS3 specification for any mention of energy in chemistry and biology and see what I’ve missed – please let me know in the comments if this has been done already!

I’ve heard – and contributed to – discussions about other possible pathways, perhaps useful for younger students. The regular suggestion is reacting, which would include chemical reactions in cells (aka metabolic-ing) as well as the lab. The shift happens between two chemical stores. The physics process, if we look closely enough, is about electron exchange between atoms. But I wouldn’t want to have that level of explanation in a year 7 lesson! As ever, the question is about us choosing a realistic level of detail for our students at any particular time.

The Power of Processes

I wrote earlier that we weren’t interested in how quickly a process worked. That’s obviously not always true; rates are very important in physics! So the process can happen quickly or slowly, which changes the magnitude of the final change in the relevant stores. This tells us that processes are about power, not just energy. (Thanks to Brendan Ickringill who pointed out the word rate is important.) The analogy I use is that of the carbon cycle. Asking how much carbon is ‘in’ plant biomass at any point is a meaningful question, if not an easy one. But it makes no sense to ask how much carbon is ‘in’ combustion, or any other process. They are rates, not amounts.

My colleague Trevor Plant reminded me of the need to change how we use Sankey diagrams for this new approach. The width of the arrow can now describe the power of the process, transferring or shifting energy between stores. A lot of the same questions could be asked, and efficiency is still a helpful consideration. We’d now think about useful processes (with values in watts) and wasteful or dissipative ones. As ever, we’d need to distinguish between similar processes; for example, energy shifted to the thermal store of water in a kettle is useful, whereas heating of the air around it is not.

Effectively what we’re doing here is describing what the ‘magical arrow of energy transfer’ is symbolising. A useful resource is a set of laminated arrows which students can write on for descriptions of the physical processes. You could provide some with descriptions on them, but the danger is that the class – or the loudest member of it – will then choose a best-fit rather than something more accurate. If you also supply laminated cards – as boxes, not arrows – with the eight stores on them, they are ‘encouraged’ towards the new model. These might be particularly useful to analyse a chosen selection from the famous energy circus.

On this theme, I produced some cards to go on the electrical sockets in the lab. The idea is to remind students that the current comes from somewhere else, and that the electrical supply is a pathway/process, not a store. Download below.

power-stations as pdf

As before, I hope the discussion here is useful – and please respond in comments if there’s something I’m missing out! Next post will be looking at stores in more detail, then hopefully a last one at the weekend on practical approaches and ways to adapt what you used to use!