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.

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!

 

Energy Language Thoughts Part 1

I was thinking ‘out loud’ on Twitter about the ‘new’ energy language, discussions prompted in part by science teachers applying the changes in their classrooms. I know I’ve blogged about energy before, but thought it might be time to have another crack at it. I’m not writing here in an official IOP capacity, although I’m also swapping these ideas with colleagues. All thoughts, responses, criticisms and offers of coffee accepted. And if you add the comments here it will be easier for others to join in, as twitter replies get lost after a while. Alternatively, as the responses to a twitter poll led me to post it in chunks, you might want to wait until it’s all done. I’ll crosspost the complete thing to TalkPhysics as well.

Challenges

  • Resistance to change – teachers as much as students!
  • Students who have learned one approach in KS3 and are now being told something different for KS4.
  • The exam boards can’t seem to agree on which stores to use and which to omit, which has knock-on effects for textbooks.
  • Teachers don’t know which answers will get marks in the exams, so don’t know what advice to give students.
  • Existing resources are incompatible with the new language – but with enough similarities to make it look like they’ll work (like a false friend in language teaching, which gives you confidence while misleading).

I don’t have answers for these. To be honest, nobody does! What I can say is that many people are trying to figure out the best way to make these changes work well for everyone. It is, in my personal view, unfortunate that they are coming in with both a specification and a grading system that are new. It’s worth noting the stores and pathways model hasn’t been recently  invented by the IOP to annoy teachers. For example: Robin Millar, Practical Physics.

There’s lots on the Supporting Physics Teaching resource from the IOP, but one place to start is this suggestion about useful things to keep in mind.

Hopefully Helpful Thoughts

A good thing about the ‘new’ language is that it encourages – pretty much demands – more attention on the actual physics. That’s the point. What is happening? So let’s start there; in any example, what process is involved? Some materials/sources call these pathways, but the idea is the same. Let’s not get hung up on labels for them, but on descriptions of actual events. It may help to emphasize to yourself that they are verbs, not nouns. They can happen fast or slow. But they involve actual physics, forces and EM and heating and so on (obligatory link to the Big Ideas of Science Education, because it’s awesome. When I rule the world every school science lab will have a huge poster of these.)

Now, these processes will change something. It means we can measure something which is different after this process compared to before. We’re not interested, right now, in how quickly this change has occurred – just that it has. This is a change – maybe a temperature increase, a greater separation of two objects, whatever – in a measurable quantity. This is associated with what we call a store. Different kinds of store have different equations, which link the measurable quantities together along with some constants. The result of that equation is a value for the energy associated with that store.

If we pay closer attention, we find that (at least) two stores have changed. What’s really interesting is that if we’re really careful, when we compare the equations, we find that the numbers are the same. An increase in one store is always balanced by a decrease in the other. The equations work as an exchange rate, showing how temperature rise in one part of the system is ‘worth’ faster movement in another part.

This, of course, is the principle of conservation of energy. Energy isn’t lost. But we can lose track of it. Sooner or later, the processes end up heating up the entire universe. Because the universe is pretty big (no, bigger than that) the change in temperature is effectively immeasurable.

So there we are; a very brief introduction to the ‘new’ model. More posts coming up, hopefully one per day. The sooner you comment, the more likely I can address your suggestions in the course of the series!

Physics Equations flashcards

So the new AQA Physics specification – currently still a draft – is interesting. Much of this also applies, of course, to other exam boards. Some of the changes I like, some I’m not so sure about. Of course a lot of these requirements were set by Ofqual and we could spend days arguing about how much of this is based on political, rather than pedagogical reasons.

But anyway.

Some schools are, of course, starting to teach this to their Year 9 pupils because they treat Science GCSE as a three year course. Even if not, those of us who teach KS3 will be looking at the specifications making sure we are setting the scene helpfully. Others have commented in far more detail than I, but I wanted to raise a few issues that have come up already during my day job.

  1. The language used to describe energy is changing, like it or not. Instead of types, the movement is towards stores (and pathways/processes) which may feel like a huge change. If you don’t know about it, please drop me a line via email or twitter, or contact us at the IOP through TalkPhysics. I blogged (personally) with some links a while back.
  2. There are required practicals instead of ISAs. (Cheering throughout the land…) Each exam board has their own list, but they’re pretty reasonable. Requirements about recording vary but it seems to me an ideal opportunity to build in regular discussion/analysis of practical tasks. SMT may need to be reminded that the list is a minimum expectation and lots more practical work still needs to be budgeted for.
  3. In AQA, at least, students will be expected to recall many more equations than previously. I’m personally dubious about memory as a proxy for leaning, but I’m not in charge. Not yet, anyway. So we will need, as early as possible, to get kids into good habits with fluent recall of these equations and their meanings, units and so on.

This last point is what I’m focused on, after a discussion with one of my mentees (the IOP runs a scheme to mentor early-career teachers of physics) over video chat at the weekend. We talked about using ideas from languages and primary spelling/times tables, where small regular testing improves familiarity. I spoke about Plickers and QuickKey as two ways to quickly collect scores for multiple choice questions. But, I reasoned, what about the students learning independently?

So today I’ve created a set of equation flashcards for the AQA (draft) specification on StudyBlue. Students could download these to their own devices for free (Android and Apple apps are available) then test themselves. Hopefully they’d customize them over time.

Set of flashcards on StudyBlue

If these seem useful, please let me know. I’m thinking about putting together sets for other aspects of the course – units and symbols are an obvious next step. So if you send me feedback, there will be more free stuff for you to use in class and save yourself time. A good deal?

Science Club: Racing Balloons

A good turnout for the second week, although some pupils hadn’t shown up despite the stories about marshmallows and spaghetti. Apparently this is a regular issue for after-school activities in primary school. Several kids were enthusiastic about telling me the scientific things they’d been doing, including building more structures with kitchen ingredients. So I think we can count the first week as a definite success!
Balloon Car Racers seemed a good next activity; simple materials, a clear outcome and hopefully something to take home. As with the other activities, the materials from the Ri ExpeRimental project gave us pretty much everything we needed.
Materials
We had 12 kids but plenty of leftovers (most earmarked for future sessions). These cost £4 from the pound shop.
  • 250 straws
  • 50 balloons (x2)
  • 100 BBQ skewers
Plus tape, card and bottle lids from general classroom resources and the local scrap store. I’d suggest collecting milk carton lids in the staffroom for a few weeks if possible.
Session
I started by asking about things that go and what makes them move. With each example – which I also used as a chance to get some more names – I added another step to the car. The video was blocked (primary school with YouTube issues) so I couldn’t use the section linking reaction forces to swimming, which was a shame.
I asked the pupils to tell me which they thought was more important – how far the car went, or how fast it traveled. Predictably, there was a mixed response! With more time I would have finished by running a ‘race’ and giving two different rankings, one for speed and the other for distance.
I used a timer on the IWB, set to 20 minutes, for the building time. This was a little ambitious, it turned out! All students had built or nearly built a car by the end of the hour session, and perhaps half had raced them against each other.
car1
Reflection
Some pupils struggled with the fine motor skills needed to use the sellotape. I don’t think I emphasized enough the need for the axles to be parallel to each other, and perpendicular to the ‘exhaust’ straw – perhaps next time draw lines on the card for them? With more time I’d have them make two, a ‘first draft’ and an ‘improved’ model. This would have been an excellent way to introduce the make/test/improve cycle, perhaps using photos of their cars to illustrate the progress. But it would have taken longer – this could easily be done over a week of lunchtimes, perhaps taking a photo each time to show the development visually. I suspect spreading it out over more time would be difficult with such young students, although at KS3 it might make a good structured project.
car3
Pushing the skewers through the lids also proved difficult for many. Next time some preparation would have been useful – especially for some lids! I’d add an awl or corkscrew for the teacher, and blu-tack to press into. A balloon pump to make up for little lungs and reduce slobber might also have been useful!
For future sessions, I’ll think through a specific ‘skills list’ before we start. Ideally the class teacher would be able to suggest particular points likely to cause problems, but I can probably manage. I’d do this automatically for my usual age group – what can they do easily, what do I need to explicitly teach – but I made guesses based on my own kids, who have always enjoyed crafty activities from Lego to junk modelling, (They haven’t a clue about football skills however, just like me.)

A Science Generation

I’ve dug out some old markbooks – electronic and paper – because I wanted to think about who it is that we’re teaching, and why. It occurred to me that having universities contributing to A-level specification discussions assumed that the courses were for their benefit. In the classroom, we as teachers adapt our examples and contexts to suit our students. We can’t adjust the syllabus itself, even if we know that the majority of our students will be progressing to a route very different to an undergraduate physics course.
I’m relying on slightly incomplete data and scribbled marginalia, plus my own memory. It’s for one ‘generation’, from year 7 to year 13, at a previous workplace (specialist science, outstanding according to Ofsted, included sixth form etc). I’d be really interested in contrasting data, if anyone has it to share – I have no idea how representative it is generally.
September 2005 – July 2012
2005 (Year 7): 240 students starting our in-house course based on the QCA topics – remember them? The students were externally assessed (following an internal annual exam) by SATs. Remember those? After they were phased out we continued with our own internally marked version. The score was used to separate students into double and triple classes for GCSE.
2008 (Year 10): 64 students started the triple course (AQA Biology, Chemistry and Physics). They were selected on the basis of good scores in their KS3 SATs for both Science and Maths, as we ‘borrowed’ some maths time for the extra science. The remaining 176 did ‘double’ (Core and Additional AQA). None could swap during the course.
At end of yr11, a large majority of those who continued to AS science courses came to our linked sixth form. A few extra students applied from other schools locally. The majority of those doing Physics had followed the triple route. (This was similar for the other sciences but not as clear.) Maths was recommended but not required,  and the entry requirement was a B no matter what GCSE route.
2010 (Year 12): 40 students started AS Physics (AQA), of which 33 were our students previously. By the end of the year, 11 had dropped the course for various reasons. Those who had studied Double science were not disproportionately represented in those failing or dropping, but those who had gained a B at GCSE were.
2011 (Year 13): Of the 29 students starting, 24 had been our students at GCSE. The cohort achieved grades from A-E, only five below C. Of these students, 14 went on to scientific degrees. Of these 14, 8 went to do physics or engineering. (6 of these had been our students from Year 7.)
science generation
Summary
Ignoring later entrants, this means of the 240 we started teaching in yr7, only six went on to physics and engineering courses: less than 3%. Even just looking at those entering sixth form as our starting point, only 20% went on to directly relevant courses.

For many students, this was exactly as planned. Some of the courses – chemistry, medicine, maths – would no doubt use the skills and knowledge gained. For other students, the more nebulous skills such as logical reasoning would be valuable in their future courses. And it’s much harder to track those who may not return to the academic content until after an apprenticeship or similar.

But as far as university physics admission tutors are concerned, those students are pretty much invisible. They’re irrelevant. What they know, or don’t know, never affects first year courses or the tutors who complain about this or that gap in their undergraduates’ knowledge.

The competing needs of ‘Science for Future Scientists’ and ‘Science for Citizens’ have long been identified, but not resolved. I’d argue that in many ways it is a situation which cannot be resolved. A few factors which we’d easily identified in our prep room cause clear difficulties:
  1. We ask our students to choose (or often, we choose for them) in year 9 or even earlier. At this point some are yet to gain confidence, while others will have already peaked, in ability or attitude. There will be a proportion of students who could go either way, but can’t be identified yet. As science teachers, we’d see this as uncertainty, not error. (Insert Schrodinger’s Cat joke here)
  2. The courses are seen, rightly or wrongly, as having different values. I’ve always said that I’d have a lot more confidence in the equal value of BTecs and similar if the same proportion of students in private and state schools did them. When an MP’s child, Tarquin or Poppy, do a college course in Leisure and Tourism instead of A-levels then maybe parity will have been achieved.
  3. Currently 16-18 courses feel very specialized. I would have loved to do more than four subjects, and it was seen back then that a broader curriculum was coming. And that, as my wife frequently reminds me, was years ago. Students feel they must identify as a scientist – or not – very young. I suspect for many it feels like a big commitment. (We looked at doing science vs identifying as a scientist in an early SciTeachJC).
  4. The very topics which might motivate students to carry on to further study are those which are less relevant for daily life. This means that it is easy for the open-ended, challenging ideas – the inspiring ones – to be saved for those students who will come to them again anyway. Those achieving at a lower level are taught topics which are less exciting – reinforcing their belief that physics is boring. A self-fulfilling prophecy!
I’m not expecting to solve anything. I don’t think I’ve even identified anything new. But when I went through the numbers, despite having taught over those years, I was surprised by just how small a proportion of our students are ‘pre-physicists’. Perhaps it would be interesting to think about the equivalent numbers at your institution?