Mr Lawrence decided to become Archimedes for the day! 

Archimedes was a famous Greek mathematician who also invened things and studied the stars. He is most famous for the time he was having a bath and noticed how water slopped out when he got in.

"Eureka!" he yelled. "I've worked it out!" because he had realised he could use water to measure the volume of almost anything. Just dunk it in the bath and measure how much water is displaced.

He was so excited, he jumped out and ran down the street, naked. Mr Lawrence thought it best not to repeat this experiment and so instead we made Trebuchets (another of Archimedes inventions!) and fired bean bags. The one that flew furthest went six metres!