Hydrogen Fuel Cells — GCSE Chemistry (chemistry only)
Pupils turn on the hydrogen, then the oxygen, and a cut-away fuel cell starts working: 1.20 V on the voltmeter, but nothing moving, because the switch is open. Close it and a motor turns — electrons travel round the outside wire, ions cross the electrolyte inside, and water collects in a jar. Cells can be stacked up to three in series (3.60 V).
The whole thing is built around one idea: when the hydrogen runs out, the cell has not gone flat. Nothing inside it was used up — it just needs refuelling, which takes minutes rather than the hours a battery takes to recharge. A button opens a fuel-cell-versus-battery card for the evaluation question.
Electrolyte toggle: alkaline KOH (as in the AQA textbook) or polymer membrane. The half equations, the direction the ions travel and which electrode the water forms at all follow the setting — so set it to match whatever your class has in front of them.
Adaptations: label detail runs at three levels with the quietest as default; half equations are off unless you turn them on (HT); moving particles can be stilled; buttons-only mode removes all 3D tapping; plus the usual Adapt suite.
Roughly two minutes end to end. Fine on a projector.