S02E17: Waves for 11 Year Olds and GCSE Required Practical

Robin and Thomas busk through teaching Sound and Waves to 11-year-olds and the Ripple Tank GCSE Required Practical.

Summary

“Physics in the News” this week looked at a story that casts doubt on the idea of dark energy. It’s a good illustration of how the scientific method and peer review is used to challenge ideas and present evidence.

Thomas and Robin chat about teaching KS3 waves and how we would introduce concepts. Robin likes Thomas’s approach of using sound vibrations to introduce wave concepts. Both love slinky springs and oscilloscopes – and don’t forget there’s a whole podcast on “Ways to Teach… waves” here. See the Summary for links to the Virtual Oscilloscope and Virtual Ripple Tank.

The core practical we discuss is measuring wave speed using a ripple tank and Thomas and Robin give the following recommendations…

  • get to know your ripple tank. Time spent getting to know your individual tank’s idiosyncrasies will not be wasted. Pick your technician’s brains!
  • Go slow. Try and get the ripples as slow as you can.
  • Look to the heavens. Try and illuminate the tank from underneath to project the ripples on the ceiling if possible.
  • Use the simulation ripple tank / wave simulation (see summary) to give students the chance to develop some familiarity (albeit simulated) with waves and ripples.

Good luck rippling!

We’re also doing a “Ways to Teach… Momentum” and a “Ways to Teach… Physics GCSE Revision” episode soon so send all the tips you can think of to us using the contact form below.

Join in!

Please share ideas or successes – or indeed questions – on our Facebook Page: https://fb.me/physicstp .  You can also message us via our website contact form at the.physicsteachingpodcast.com, Twitter @physicstp, email using  the address given in the podcast (if we remember) or by leaving a voice memo using WhatsApp or Telegram to the phone number in our Twitter profile, +44 7898 814716 (don’t call the number, nobody will answer, just hold down the microphone icon and speak your message or upload an mp3 or ogg). Don’t forget to tell us your name because we may use your audio in a future episode.

The music we use remains One legged equilibrist polka by Circus Homunculus. The music before and after James is Cantina Rag by Jackson F. Smith.

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27. Ways to teach… Waves

Thomas, Robin and Patrick introduce and discuss many ways of teaching waves that have been shared by the listener.

Timestamps

  • Physics in the News – Blue Origin @ 01:07
  • Ways to teach… Waves @ 01:50
    • Cara Wood and a piece of string @ 02:20
    • Slinkys @ 06:50
    • Making many nodes @ 10:54
    • Salt Pendulum @ 13:47
    • Acetates @ 14:58
      • Jed’s wave visualisation experiment @ 16:48
    • How to remember the difference between Transverse and longitudinal @ 18:59
    • Alom Shaha and the Jelly Baby Wave Machine @ 20:17
    • Standing waves @ 24:51
    • Ruben’s Tube and Kundts Tube @ 28:01
    • Showing colour mixing and projector polarisation @ 30:43
    • Young’s slits – lab scale with sound @ 32:47
    • PhEt @ 33:38
    • Mexican Wave @ 34:20
    • Tell us misconceptions! #tptpmisconception @ 35:25
    • Who won Alom Shaha’s Book? @ 37:43

Summary

Patrick, Thomas and Robin get together to tackle ways to teach waves but not until they have touched on Jeff Bezos’ bid for extra-terrestrial adventure: Blue Origin.

Cara Wood was first up sharing tips for teaching waves.  She introduces waves by simply getting students to pluck a piece of string held in their teeth, so that they can see, feel and hear vibrations, experience amplitude and frequency, and discuss waves travelling through solids and gases.  Patrick loved this: really giving a tactile encounter with waves and their source.  Robin made the tenuous link to cochlear implants.  Very similar is the metal coat hanger demo.

“You can’t beat a Slinky” according to Dan Toomey – thanks Dan!  Patrick put us onto “Snakey springs” on amazon for a mighty £27, but we found them cheaper with a bit of persistence: £5.75 at Select School Supplies. Snakey Springs help to avoid Slinky tangles when demo-ing transverse waves.  Thanks to Graham Thomson for the tip of setting a ball next to the slinky spring so that it gets struck as the wave passes and you can thus link frequency and energy.  Graham pointed out the rich discussions you can have on time period, frequency, wave speed and wavelength all with the Slinky.  Thomas was really impressed with Frank Noschese’s video using paper cups next to the Slinky to demonstrate constructive and destructive interference.  Robin recalled a similar method to this to demonstrate the vibrational link to sound waves.

Frank Noschese masters the Slinky

Thanks to Dr Joshua Griffiths and Graham Thompson who talked about challenging students to produce features on ropes and Slinkies, such as increasing numbers of standing waves and purposely frustrating by asking for high frequency, long-wavelength waves.  This gives a good discussion of why it can’t be done!

Thanks to all the other folk too numerous to mention, who also pointed us towards the Slinky as a ‘must-have’ for teaching waves.

Thanks to Dan Toomey for the salt / sand pendulum video.  Thomas was delighted to report he had already done this and Patrick was keen to have a go.

John Hamilton’s use of acetate wave traces to demonstrate superposition makes a tough concept much easier for students to visualise – thanks John!  Jed Marshall uses acetates to get across the tricky idea of wavefronts, alongside his ripple tank that students can struggle with and he kindly supplied a booklet to show how it worked. (photos below).

How’s this for a handy mnemonic for longitudinal vs. transverse?  Thanks to Chris Beason and K Physics 1.

Alom Shaha joined us for his PIM and he described his jelly baby wave machine. The video says it all: easy to make, and as Alom says, transformative in the teaching of waves! Reflection, refraction, amplitude and frequency – all easily demo-ed quickly and cheaply. Despite Jelly Babies being lost in translation, Patrick endorsed the machine and he still uses it, although the Gummy Bears may be past their sell-by date!

Signal generators, strings and vibration generators always go over well, particularly in conjunction with a stroboscope and Patrick described how he challenges students, not least through atmospheric use of Pink Floyd music! Don’t forget your Rubens tube too – it really helps discussing pressure differentials in sound waves. And if anyone has any tips to get the Kundt’s tube to work, let us know!

Paul from @PlanetReynolds on Twitter had a lovely dichromatic crystals demo which has “Wow factor” and his toppling dominos is a great way of demonstrating density’s effect on wave transmission. Just search on eBay for “optical glass cube” and “100 led finger lights“.

Thanks again to Dan Toomey for his tip on using superposition with loudspeakers, and don’t forget PhET, ripple tanks and “stadium waves”!

…and finally! Well done to Frank Noschese who we picked from the expensively engineered randomised name selection device. Frank will receive a personally signed copy of Alom Shaha’s Recipes for Wonder.

HAVE A GREAT HALF TERM!!

Join in!

Please share ideas or successes – or indeed questions – on our Facebook Page: https://fb.me/physicstp .  You can also message us via our website contact form at the.physicsteachingpodcast.com, Twitter @physicstp, email using  the address given in the podcast (if we remember) or by leaving a voice memo using WhatsApp or Telegram to the phone number in our Twitter profile, +44 7898 814716 (don’t call the number, nobody will answer, just hold down the microphone icon and speak your message). Don’t forget to tell us your name because we may use your audio in a future episode. Please do leave a voice memo: Thomas thinks nobody loves him.

The music we use remains One legged equilibrist polka by Circus Homunculus.

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