Skip to 0 minutes and 2 secondsTOM LYONS: Thank you for taking part in the teaching practical physics course. We've enjoyed reading all your responses. We've got a couple of questions that have come out that we're going to have a look at today. So we're going to start off with one both from Lucy and Kirsty, who were asking about potential difference and ways to teach that. And one way to look at a potential difference is if you, for example, have a wire and you want to look at the tension across that wire. If you have a piece of constantan wire, it is quite good to use. You can divide that wire up into sections.

Skip to 0 minutes and 39 secondsIf you have, say, one metre of wire, and then you take half the length of that wire and you measure that with a digital multimeter, then you can see that that half, that distance, is half the potential. Another kind of question around that, which Kirsty said, is any other ideas of how to teach it. Perhaps an analogy that you could make with it is if you look at the gravitational field, it's analogous to the electric field.

Skip to 1 minute and 9 secondsSo you could look at potential in the gravitational field, for example, by raising a mass in the gravitational field, looking at the change in energy of that mass, and relating that to when you've got charges in an electric field, as you have in a circuit, going across the battery or raising the potential energy of that charge. It's the same thing. So looking at gravitational potential difference and comparing to potential in an electric circuit.

Skip to 1 minute and 39 secondsADAM LITTLE: And yes, just to add to that. One simple way I start off with-- if it's a Key Stage Three GCSE, it's just getting students to understand what the term potential difference actually means, because they generally get that confused quite a lot. So one thing you can start with is just getting a simple cell and having it there, getting your volt metre, and plugging it either side and showing the reading. So if you have a six volt cell, for example, the volt metre should read six volts. To say, has no energy at this side. As it's gone through it's gained six volts, or it's got that energy, as it's gone through. Then taking that apart, you build a circuit.

Skip to 2 minutes and 17 secondsYou can then put a bulb in there, and then show how the six volts that have gone in, then come out six volts in the bulb, for example. And then by adding bulbs you can see how then, that is split up. And there's a difference from where it enters that component to where it leaves that component. Hence the term potential difference.

Skip to 2 minutes and 38 secondsTOM: So we had a couple of questions around safety. One on radiation, and one on high voltage supplies. The best thing to do there is to refer to the health and safety guidance that you have nationally-- so it would be CLEAPSS in England, SSERC in Scotland, for example-- and refer to those when you're looking at any kind of safety aspects.

Skip to 2 minutes and 58 secondsADAM: Just leading on from that as well, the CLEAPSS and the SSERC websites are excellent sources for if there's any equipment that you have issues with. And one of the questions we had was about setting up and oscilloscope to show an AC supply. So once again, I would refer to the CLEAPPS website, or SSERC's website there, for guidance there. Also the Institute of Physics, on their website, have a step by step guide on how to set up an oscilloscope for an AC supply, which is really handy. Especially for non specialists who might not be used to that equipment.

Skip to 3 minutes and 34 secondsTOM: We had a question about cycle dynamos, and what's the best way of showing how it works. What I would say for that is, if you can, take a cycle dynamo, take it apart, and show the movement of the magnet inside the coil. Try and set it up with a metre and actually watch the voltage change. Or set up your own version of it, if you can't do that. So it's basically moving a magnet inside a coil to show the change in voltage or current.

Skip to 4 minutes and 8 secondsADAM: And another question we had was from Richard, who is asking about real life applications and contexts for physics, especially at Key Stage Four. And asking say, for example, about how to make specific heat capacity interesting and relevant to students. As opposed to just, here's a piece of aluminium being heated up, and exploring what happens. So one example I like to give is things like metal that you put in the oven. And that when you're baking something, when you take something out, you use oven gloves because the metal is hot, and then you put it on the side.

Skip to 4 minutes and 44 secondsWhereas five minutes later, you're OK to pick it up with your hand, because it's been able to dissipate all that energy because of its specific heat capacity. There's also the example, as well, of the sand on the beach and the water at the seaside. That during the middle of the day the sun is extremely hot, yet the water is cooler. And then after evening when the sun has gone down, the sand has cooled down quicker than the water, and the water is still warm. Which is one of the reasons why when I'm on holiday, I always get perplexed why people are still in the water after evening. And then I remember, specific heat capacity.

Skip to 5 minutes and 20 secondsTOM: And then water is a really nice one, actually, to use for investigation. So you could, for example, use the idea of water-- what's the best way of cooling down drinks. So is it best to use ice? Could you use salt water, which has a kind of lower freezing temperature? Could you use something like whisky stones or some ceramic material to cool things down? And do an investigation to see which one of those keeps the drinks coolest for longest, and trying to think of ways that you can engage the children with that.

Skip to 5 minutes and 51 secondsADAM: Another question we had was asking about when you've got to do whole-class demonstrations and you've got a lack of equipment, which is a common complaint from a lot of people around the country. And one thing I would suggest, or one thing that I've seen work really well, for example, is taking videos of this on your mobile phone. And then uploading them to YouTube, and then being able to show them on a big screen to a lot of students. For example, when you're making motors at Key Stage four in electricity. When you're modelling that at the front of the class, you might have your 30 students sat around.

Skip to 6 minutes and 29 secondsBut it's that intricate, it's that detailed, that only the first row of students might be able to see exactly what's going on. And the other students start losing interest because they're not able to see, and you have behaviour issues and various other things to deal with. Whereas if you film it beforehand, and you're able to get in really close, the students are able to then see this on a big screen and then all focus on that video. Whereas you can keep your eye on the students while this video is playing, as well, which helps reduce behavioural issues. One example I've seen if this is a YouTube channel by a school near Leicester called Judge Meadows Science.

Skip to 7 minutes and 5 secondsAnd if you look at them, they've got lots of required practicals, how to make motor kits. There's lots of YouTube videos out there that are really good, so I'd highly recommend watching those. And if you can, and you're feeling brave enough, making your own as well. And leading on from that, as well, is the lack of equipment, and people saying how can we demonstrate things like light gates, and various other things. With the technology we have now, things are coming down in price. And one thing I would recommend is-- we have these very small light gates here that are called BeeSpi V light gates. And these are about 20 pounds from Amazon.

Skip to 7 minutes and 43 secondsAnd these can be used to measure balls rolling through, and can be used to measure speed. And there are timers and various other things. So if you can't afford big, complex light gates that plug into computers, which half the time don't work anyway, this is a great, cheap alternative that you can get students to use. And like we've just said before as well, you might want to do some filming. Perhaps borrow some equipment from a school. Or if you go on CPD courses, like face to face at STEM Learning here, you're able to film them in action as well, take them back to school, and use those videos in your classroom.

Skip to 8 minutes and 20 secondsTOM: Yes. And I'd say another thing that you could do would be if you had a small group of students demonstrating to the rest of the class. And you have to look at the safety aspects of that, and whether they would feel confident. But you could get them to demonstrate. And then as you're doing different lessons, you have different groups demonstrating, and that kind of engages them and the students in that activity as well. We had a question, moving on. Maria asked about links to electricity in real life situations. And there's probably quite a few of these. I was just thinking and about trains, actually.

Skip to 8 minutes and 59 secondsAnd in terms of the electric cables that are used for those, there's a switch at the moment going from ground-based over to overhead rails. And you could, if you're looking at AC and DC power with that, you could look at the overhead cables are at 25 kilovolts, and the ground tracks are at a lower voltage. And you could start talking about why would you use a higher voltage,-- works for electric pylons as well. What are the safety aspects of that? What's the advantages of that, as well. And also maybe something as simple as your toaster in the kitchen. Why are you always told not to stick a knife into the toaster when it's on? What could happen there?

Skip to 9 minutes and 43 secondsWill it always give you a shock? You can start talking about electrical resistance in that case, as well, path of least resistance of the electricity. We had a question from Colin about how you can get students to come up with an equation without you basically telling them. So looking at doing a practical, seeing the relationship between measurements. And one way to do that is to actually get them to plot the measurements on the graph. That way they can, if they're familiar-- they should be familiar in maths with things like y equals mx plus c, straight line graphs, maybe quadratics. If you get them to plot the results on a graph, and then put a line of best fit through it.

Skip to 10 minutes and 25 secondsHopefully they can use their maths skills to come up with some relationship for that.

Skip to 10 minutes and 31 secondsADAM: And just referring back to what you will have seen as you made your way through the course, one of the examples we gave when we looked at waves was just getting the tray, a metre ruler, and a stopwatch. And just trying to find out the speed of the wave. You're giving the students no more information, and they've got to try to figure out, well, how can I work out the speed wave. What information do I need? And by having a metre ruler, by having a stopwatch, then they'll start to see, well, it obviously links the distance. It obviously links to time. And then getting them to work out that equation, and derive the units, for example.

Skip to 11 minutes and 5 secondsThat is quite a powerful tool to get them to have a deeper understanding of the topic they're taking.

Skip to 11 minutes and 10 secondsTOM: And Helen mentions in her question about using PhET simulations for things like conservation of momentum, because the trolleys maybe don't give you the right result. Things like simulations, particularly from PhET, are very good to use to give you kind of ideal results. But it's always good to actually have a non-ideal situation, where you are maybe losing energy in the system. If you've got some dynamics trolleys that are not quite giving you the right results, then you can talk about what's happening there, where are the other losses, and where's the friction there. And so it's not necessarily always the best thing to have it working in an ideal way.

Skip to 11 minutes and 53 secondsADAM: I think with a lot of physics practicals, and physics teachers, and non-specialists alike will turn around and say, physics is the science that never works. And it's true. A lot of the time, things don't work out the way they should. Physics tends to try to make life easy. For electric circuits, for example, we say you put six volts in, you'll get six volts out. But that never matches the readings on the volt metre. And getting the students to talk about why they're not getting the right results-- so why isn't it exactly three volts and three volts on two identical bulbs? Why might it be 2.97 and 2.96, for example?

Skip to 12 minutes and 35 secondsBy getting them to discuss that, and why the results aren't what they expected, if they're coming out with the good reasoning behind it, they're showing that deeper understanding. They're showing they do understand that. And let's face it, if science worked all the time it wouldn't be as exciting as it really is. Once again, we just want to thank everyone for doing our physics course. We hope you enjoyed it. Please do let us know if there's anything else you'd like to know moving forward into the future, so we can help provide you with that information. And also don't forget that you can come here to the STEM Learning Centre.

Skip to 13 minutes and 12 secondsFor example, in March time we've got our Inspiring A-level Physics course, where you can look at things like origami robots, and nanotechnology. And swallowing these little robots that can go into your body, perform an operational task, then fold themselves back up again. And monitoring seahorses heart rates, to test water pollution, looking at sound chambers, and various other things like Music technology. And being able to give that everyday context to many different science principles.

Skip to 13 minutes and 43 secondsTOM: And with my space hat on, or should I say my space helmet on, we've got the STEM Clubs in Space, course, coming up in March as well. So if you're a teacher or a technician and you want to run a STEM Club, then we've got some great resources for you there to look at.

Q&A with Adam and Tom

The Q&A sessions on courses from the National STEM Learning Centre provide you with the opportunity to ask more about the course content and issues from your own classroom practice.

Adam Little and Tom Lyons recorded their answers to outstanding questions from your reflection grid and discussions on 4 December 2018. Thank you to all who contributed and posted their questions. The topics, with some additional links, are below.


  • 0m07s - Teaching potential difference
  • 2m38s - Health and safety (radioactive sources, high voltage power supply) - CLEAPSS and SSERC
  • 3m08s - Setting up an oscilloscope - IoP video and step-by-step guide
  • 3m34s - Using dynamos
  • 4m07s - Real life applications (specific heat capacity)
  • 5m51s - Required practicals with lack of resources - Judge Meadows Science YouTube
  • 8m43s - Real life situations (electricity)
  • 9m52s - Students deriving equations
  • 11m10s - Simulations and getting the ‘right’ results

Please note: if you post a question here it may be featured in the video recording along with your first name. The recording will be publicly viewed via this step and may also be uploaded to the STEM Learning YouTube channel.

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Teaching Practical Science: Physics

National STEM Learning Centre