The Physics Teaching Podcast

Tag: electricity

  • Retention Done Well

    Retention Done Well

    We talk to Doug Simon, who takes issue with the assertion that CPD is not C, P or D for Physics teachers.

    Having heard from Mark Whalley last episode about some of the gotchas that schools can fall victim to when trying to hang on to their (physics) teachers, we hear this week from Doug who reports some of the positive things they do to support their science teachers and keep them teaching.

    First up, though, Thomas and Robin talked electricity as that is what they both had been doing this week.

    Thomas had demonstrated a bit of uncertainty that GCSE students can get their heads around: the meters sometimes lie! See below…

    Thomas’ three ammeters and three voltmeters reading randomly

    This is a nice way to introduce a discussion on precision and accuracy in measurement.

    Robin had been investigating LDRs and Thermistors and trying to avoid the pitfalls he has hit in the past – either it takes waaaay too long, or it causes cognitive overload with all the fussy details: digital multimeters on the ohm setting, light meters (probably for the first time), multiple experiments, different scale settings with different units, new circuit symbol (ohm-meter anyone?). Doing both together might seem odd, but if you emphasise that both experiments are effectively looking at the same thing – an energy transfer changing resistance – students can see parallels. You only have to set the DMM up once, and I always explain that it is doing what they did recently: measuring voltage and current at the same time and working out R for them – they like that. There are better ways to teach this, sure, but this is ‘quick and dirty’ if you are short on time (and we always seem to be!). See the thermistor practical in the links section – thank you Mrs Cook! I hope you are still teaching physics.

    … and talking of still teaching, back to Doug who gives us practical advice on how science teachers can be nurtured and recognised. Some highlights:

    • a specific period per week to support planning & teaching
    • commitment to the subject in department meetings (not exam admin, other initiatives, safeguarding etc.). Meetings are used for discussion / CPD
    • CPD for teachers in meetings based around answering tough questions / misconceptions and ways topics have been taught.
    • Ensuring a common language in maths. Where skills are common (e.g. rearranging equations) can you provide physics-based maths exercises to your maths colleagues?
    • 6 periods per fortnight for KS4 science.
    • specialist physics technicians whose CPD is also worthy of investment.

    Doug’s school has had success in holding on to their teachers – it can be done! Why not reach out to a school doing good things and keeping science teachers? Culture can make a real difference and Doug’s school has shown how positive culture can help a school keep its teachers.

    Thanks to Doug for getting in touch. Do let us know if you have anything to share with the physics teaching community. It was great for us to be in contact with Clare Harvey from the Ogden Trust this week (we’ll hear from her on the podcasts soon). the Ogden Trust do great work supporting physics teachers and we will be hearing about their work and how they can help support your practice.

    Links

    Join in!

    Please share ideas or successes – or indeed questions by messaging us on BlueSky: https://bsky.app/profile/physicstp.bsky.social .  You can also message us via our website contact form on every page of the web site at  the.physicsteachingpodcast.com, or email using the address given in the podcast (if we remember). We are moving away from X but can be found there as @physicstp.

    Music

    The music is used under the Attribution-NonCommercial 3.0 International License

  • James de Winter is Electric

    James de Winter is Electric

    Season 3 continues to deliver physics royalty as James de Winter joins us. James is the physics tutor on the Cambridge PGCE course and has seen generations of physics teachers through their training. Having met a fair sample I can say that all of them hold James in the sort of reverence that Luke reserved for Obi Wan.

    A talk with James is always an education and this episode is no exception. There’s lots to think about in terms of reflection on your lesson: James encourages us to stay as practical as feasibly possible during these strange times. Practical work has a far more tenuous grip in schools than it should, and there are a number of reasons for this, but the Covid crisis is yet another obstacle, so please please safeguard investigation in your classroom.

    So you may think that you should always have a practical investigation for every lesson.. well, no. As James points out, we need to think about our rationale, and how to tackle the obstacles and what we want students to walk away with after their experimentation.

    Robin rambles on a bit about the PhET simulation, and if that appeals, we’ve posted a link below.

    James makes a good case for LEDs instead of bulbs for circuit investigations – they’re more reliable, they’re cheap, they’re directional and they are more consistent than incandescent bulbs. We’re interested in hearing how you get on!

    We move on to a discussion of then classic core practical “Investigating how current varies with voltage across a component”. Thomas tells us to have a working version of then circuit for the students to look at, and James urges us to give this practical a firm context. If your students haven’t got a good appreciation of voltage and charge, they won’t squeeze the most out of this investigation. James’s advice: make sure you know the narrative that you want the kids to walk away with.

    A discussion of the micro and macro worlds led to a word of caution from James: we need to recognise that our comfort moving between the large and the small scale is almost certainly NOT mirrored by the students and so we should identify that as a skill that we should explicitly teach.

    Oh, and James’s practical in memoriam is measuring the resistance of an 8B pencil line.

    Links

    John Hudson’s Radioactivity GCSE AQA – interactive independent study pdf on the TES web site.

    The PhET circuit construction kit.

    Join in!

    Please share ideas or successes – or indeed questions by messaging us on BlueSky: https://bsky.app/profile/physicstp.bsky.social .  You can also message us via our website contact form on every page of the web site at  the.physicsteachingpodcast.com, or email using the address given in the podcast (if we remember). We are moving away from X but can be found there as @physicstp.

    Music

    The music is used under the Attribution-NonCommercial 3.0 International License

  • 10. Ways to teach… Electricity

    10. Ways to teach… Electricity

    Merry Christmas Physics teachers!  In a bumper festive edition, Thomas and Robin have rounded up your ideas and tips on how to teach electricity.  It’s quite rare to reach a clear conclusion in a discussion of teaching, but there was consensus that if you are going to use a model, then the rope model is a great starting point, and Thomas has written a full description of a way to use the rope model in his blog.  We also acknowledged some other models and their usefulness: the important thing is to reflect and evaluate, but then again isn’t it always?

    Resources

    You can see all the tips and suggestions in a gallery at the bottom of the page.

    We were delighted that the excellent PhET resources were mentioned by a couple of people. There are several electricity simulations, for example the DC construction kit.

    Robin mentioned the Supporting Physics Teaching Web site, and its resources on electricity. It’s a great resource but is more akin to an Encyclopedia than a guide.   For a nice clear description of the rope model read the article by Tom Norris about teaching electricity. Tom also sent us a message after the interview:

    Traditionally, in ks3 electricity schemes, you teach the electricity concepts, and *then* comes a lesson where you teach about electricity models. I personally wouldn’t do the “evaluating models” lesson unless I’m happy students’ understanding of electricity itself is at an expert enough level to be able to spot the subtle nuances of what the models do well and not so well. And also, secondly, because I don’t think knowledge of electricity models is anywhere near important enough to give a whole lesson to. The most important resource physics teachers have is time, and I the electricity topic I want to spend every lesson teaching about electricity itself. I don’t see electricity models as ‘content for students to learn’, rather, electricity models are something that I, the teacher, turn to, to help me explain/demonstrate the electricity concepts that I’m teaching.

    Tom Norris

    Lucky shot of an arc sparking

    Thomas was delighted by the idea of driving a aluminium foil capacitor with the EHT. He duly did it and was delighted with the results.

    What an exceptional community we are building!  All of this week’s podcast came from our growing listenership, so a million thanks.  Keep spreading the word, and if you liked the slightly different format (or not!), do let us know.  Similarly, if there’s anything you’d like to cover, please do share.  We plan another special on energy soon.

    Have a good rest and we’ll see you in the New Year!

    Join in!

    Please share ideas or successes – or indeed questions by messaging us on BlueSky: https://bsky.app/profile/physicstp.bsky.social .  You can also message us via our website contact form on every page of the web site at  the.physicsteachingpodcast.com, or email using the address given in the podcast (if we remember). We are moving away from X but can be found there as @physicstp.

    Music

    The music is used under the Attribution-NonCommercial 3.0 International License

  • Using The Rope Model of Electricity

    Using The Rope Model of Electricity

    In the next podcast we inevitably talk about the rope model. I tried it a few times in the past and hated it ?. It was only in making the podcast that I finally understood how to do it and how good it is. Not knowing how to do it is as much a function of my comfort with the donation model as it is my being alone in my school with no other physicist to talk to. But talking to Robin and Stuart about electricity really got me thinking. 

    When I did the rope model it didn’t work because I had quite a few kids involved in the demo. I found it really hard to make the rope run smoothly through their hands (not least because the rope had a huge knot in it!) and it was a very static sort of demo. There was no fluidity at all, no flow. I had visions of attaching pulleys to the walls of the room to make it work (I like big scale). I chatted to Stuart about this and he was able to tell me a way to do it that worked. It works so well, and is so easy to do. I was bowled over.

    my recipe for an effective rope model demo:

    1. Have a rope that is in a 3-4m loop where the join is as smooth as possible. (Cutting and melting together a rope is ideal).
    2. Choose one student only.
    3. Hold the loop and pass the other end to the student. Tell them to grip it lightly (they don’t want rope burns) in one hand with the rope passing vertically down through their fist (this is the detail I never understood – one student, one hand).
    4. Explain that the rope is the electrons and the grip is the resistance.
    5. Pull the rope hand over hand through their (one, stationary) hand.
      • Question: What do you feel in your hand? 
      • Answer you want: Warmer
    6. Tell them to add another hand, holding with the same light grip. The rope will get harder to pull, make this obvious, it will naturally run more slowly.
      • Question: why is the rope moving more slowly?
      • Answer you want: because there is more resistance.
      • Question: how can I increase the current to make it move as fast as before?
      • Answer you want: Pull harder.
      • Explain that this means more energy being delivered by the cell to the rope, or greater pd.
    7. Pull harder, to make the rope move at the original speed again.
    8. Tell them to grip tighter with one hand, but not to tell you which hand that is.
      1. Question: what has happened to the rope speed?
      2. Answer you want: slower.
      3. Question: does the rope/the pd know which hand is gripping harder?
      4. Answer you want: no.
      5. Question: what is happening at the tighter hand?
      6. Answer you want: warmer.
      7. Explain how this is energy transfer
      8. Question: are the electrons in any way different before and after the hands?
      9. Answer you want: no.
      10. Remind them that electrons just go where they are pushed/pulled by the pd, they aren’t changed, they don’t make a choice, they just go where they go.
    9. Get another rope, get them to hold one loop in each hand, but you pull them together. You can model parallel with this but I wouldn’t go too far as the model does tend to break down a bit.
    10. You can show AC nicely too. Remove one loop then tell them to hold their fist horizontally, not vertically. Now grip the loop in both your hands and pull it backwards and forwards. The hand gets warm just the same.

    Good luck with this. Maybe report back in the forum?

  • 9. Mentors, Motors and Merch

    9. Mentors, Motors and Merch

    Robin hadn’t heard about the recent Falcon landing failure so Thomas filled him in.  Cutting-edge space technology is still frontier science: we need your students to be the engineers of tomorrow!  Regular listeners will know how much Matt Groening influences the podcast, and just in time fro Christmas, we have launched our first ‘merch’, setting up a shop on the web site.  A shop where you can buy the T-Shirt? Yes, all your Christmas present problems are solved!  Listen out for a secret (??) code that allows you to get your shirt at cost. This time next year we may be stocking TPTP box sets and underpants: our ambition knows no limits.

    Care in the community…

    Physics teachers can be empathetic too! Robin worries about how hard this time of year can be, and especially for young-in-service teachers and the terrific Jo Kent draws on her wealth of experience to give her advice. She highlights how an empathetic ear can make all the difference, and on a more practical note, how networking can help to build communities.  She specifically mentions TalkPhysics and Thomas compares it to PTNC. (The IoP has a page where several other ways of networking are listed). Jo goes on to tell us about her Pint Pot Motors in a Practical In Memoriam. Below you can see the images she talks about below and she also sent us her PowerPoint and the video her father made.

    It remains a privilege and a joy making this podcast for you.  We love hearing from you and you are a very big part of the adventure; guide us, tell us what you want to hear about. It really is your podcast, so please get in touch: teachers of physics are our very favourite superheroes! 

    Jo’s Pictorial Instructions

    A Working Motor

    The Motor Jo’s Dad made:

    Also Thomas made the motor and shared it on Twitter:

    Join in!

    Please share ideas or successes – or indeed questions by messaging us on BlueSky: https://bsky.app/profile/physicstp.bsky.social .  You can also message us via our website contact form on every page of the web site at  the.physicsteachingpodcast.com, or email using the address given in the podcast (if we remember). We are moving away from X but can be found there as @physicstp.

    Music

    The music is used under the Attribution-NonCommercial 3.0 International License