Light-speed learning

In the classic microwave oven demonstration to determine the speed of light, you remove or invert the oven’s rotating base plate and put a plate of food, like marshmallows or chocolate, within to heat. Students get tasty rewards for participating, but there are a number of issues with this version of the demonstration. Try heating thermochromic ink on paper instead. Quick results with centimetre resolution allow students to practice taking measurements, doing calculations and analysing errors.