A favourite activity for younger children is to find out how long they can stay in the air when they jump. These large mats (58cm x 17cm) are on/off switches, and are activated by stepping on to them; one mat starts the timer, the other stops the timer.
Activities
9 - 12 years
How long can I stay in the air when I jump?
How fast can I hop, walk, run?
How many jumps can I do in a minute?