school timer

[linus20]

school project, draw and make a device that can time 30 seconds, any ideas please

[WendyW]

How about using a Water Clock

[sft42]

if it doesn't have to be an original idea you can't beat an eggtimer no pun intended.

[JiverSteve]

A ball running down a shallow track

[happyducky]

i like the idea above but an egg timer is just as good. just use a stopwatch to time how much sand needs to run through to keep going for thirty seconds then you'll now!