Building a Chinese Water Clock

To make your own water clock, just follow these steps:

1. Take two disposable plastic cups. Poke a small hole in the bottom of one of them. Cut a larger hole (almost the entire bottom) out of the second one. 

2. Tape them bottom to bottom, then stand them up in a medium mixing bowl with the pin-hole cup on top. 

3. Make a mark near the top of the cup with a permanent marker. Then, fill the cup with water up to the mark you made. Can you predict how many minutes worth of water the cup holds?

4. Time one minute and mark the water level. Continue timing minutes and marking the water level until the cup is empty. 

Now, you can time activities using your water clock! How long does it take to tidy up the living room? How long can you stand on one leg?