Two clocks
I was chatting to another physics teacher, Chris Folland, at a workshop in Malta the other week. We were talking about how we physics teachers like neat solutions to simple problems and he told me about a really neat idea some of his students came up with. It's a way of accurately measuring a time with two stop clocks. Its so good that you could do a g experiment with drops of as short as 50cm (maybe less) and still get a good result. You need two students one starts clock 1 when the ball is dropped the other starts clock 2 when the ball lands. They then put the clocks together and stop them at the same time, the difference gives the time of the drop. Neat.