I cannot accurately recall how long I had been teaching when the box of bits came into existence, or maybe the question is how many bits constitute a box. My first teaching post involved teaching in five different labs and a classroom – not conducive to accumulating stuff. It was only in my second teaching post where I had my own lab, and was able to accumulate those odd items which could come in handy during lessons.
The box of bits started out simple. Springs and a couple of masses allowed demonstration of extension, the spring constant and the effect of loading a spring beyond its elastic limit. They also provided a visual stimulus for energy stored in a spring, and as an analogy for energy stored in a capacitor.
A mass with a length of string frequently demonstrated aspects of simple harmonic motion. Later in the year the mass was replaced by a rubber bung to demonstrate factors affecting the orbit of satellites. The advantage of string and a mass over whizzy simulations is that they are tactile. The apparatus can be amended at will to match learners’ specific questions, or adapted to cover the unexpected misconception.
Next concept: gravity, starting with 5¼” floppy disks. Our ears are great discriminators of sound, quite capable of identifying whether two objects hit the floor at one time. Dropping combinations of one, two or three disks at the same instant, I demonstrated that they hit the floor with a single clatter and so had accelerated at the same rate. Thankfully, the laws of physics apply equally to 3½” floppy disks, so I was able to move with the times.
A collection of balls found its way into the box: a ping-pong ball, a squash ball, a tennis ball and a medicine ball. (Alright, I lied about the medicine ball. That was in the cupboard, along with the skateboard, a guitar and some bigger stuff.) Balls allow very simple demonstrations of momentum: no matter how hard you throw a ping-pong ball it has very little effect on impact with a stationary tennis ball. The decay of bounce height, possibly filmed on a mobile phone, allows you to discuss coefficient of restitution and other aspects of elasticity and bounciness. That may be beyond the specification, but adds to understanding of exponential decay.
A memorable demonstration, though pure physicists may consider it flawed, relies on keeping a few balloons back from any lesson when you are allowed them. Inflated balloons on the floor represent atoms, and the balls from your box are photons with differing energy levels (ping-pong ball is radio waves, squash ball is microwave, and so on). See what happens when you drop a ball onto a balloon. Smaller balls will move the balloons, with the increase in kinetic energy modelling the increased thermal energy. The medicine ball, representing X-ray or gamma photons, is likely to burst a balloon – a model for ionisation.
Finally, add to the box small pieces of stage lighting filter in shades of red, green and blue, just to reinforce that yellow is not a primary colour. A 30 cm length of transatlantic fibre optic cable to demonstrate that most of the volume is protective layers for the glass fibre. Two or three transformers with laminated cores and one with a ferrite core, which will pose the question as to what is different about the ferrite material.
There may have been more bits, or bits that only lived in the box temporarily, but this gives a flavour of my box of bits and the uses I put it to. For more information about OCR's approach to the Practical Endorsement visit our Positive about practical webpage.
Submit your comments below and tell us what bits and bobs you use to make your lesson exciting. If you have any questions or would like more ideas then you can get in touch with us via email firstname.lastname@example.org or on Twitter @OCR_Science.
Neil Wade - Subject Specialist - Physics
Neil joined OCR in May 2014 having taught GCSE science and A Level physics for the previous 19 years. Neil has represented OCR on the cross-board working group for the Practical Endorsement, looking at its implementation both nationally for all boards and at the OCR approach to practical work in the new specifications.