In fact, I remember first seeing it as a trainee and thinking 'wow, how clever' until I started to think about it and work out numbers of moles and stuff.

I knowit's a very good visual thing but it's all wrong and I can't bring myself to do it.

Yes, you would!  That experiment is not in the sample lesson plan, which chooses the candle experiment as #1 demo, but it is listed in the scheme of work elsewhere 'A second example is the two gas syringes connected to either end of a small tube containing copper...'

I think I remember watching the candle experiment when I was about 12, and being too ignorant to question it.  Distressing that it is still being taught this way ** years later. Who writes these schemes of work anyway?

If you actually did the experiment in the way the surfing scientist link suggests (probably with a top GCSE set, or an A level chemistry group) it could be really educational, you could discuss misconceptions, talk about how easy it can be to draw incorrect conclusions, and then plan further experiments to prove/disprove the various theories.

I should also add that the result you get will depend on the shape and size of the jar and the length of candle you employ.

An experiment in 21st century?

Ah, only a demo,and a wrong one. This was supposed to be the jewel in the crown of modern science education - and it's so badly structured - and boring.

Then last year OCR were giving grade A to candidates who got half the C456 paper wrong followed by us wondering why our A level students struggled so much. 21st century has really put me off my job.

Sadly the deathly silence from OCR remains unbroken. Has been over a fortnight now.  Will let you know if they ever reply, but I'm not holding my breath.

Still, my own kids - KS1 age - had a lot of fun the other day in the kitchen demonstrating that we could easily displace 38% of the air from a large coffee jar using 4 small birthday cake candles (that's some impressive 'oxygen consumption!').  1 candle displaced 17%, for reference.