As part of a recent physics class, students at Young Americans Christian School were asked to build "trebuchets" that could launch a water balloon at least 15-20 yards.

A trebuchet is a machine powered exclusively by gravity, typically by means of a counterweight. It utilizes a sling affixed to the end of the throwing arm, acting as a secondary fulcrum.

Students' grades were based on design, calculations, individual contribution and accuracy. Groups of three to five students worked together and could earn extra credit for complicated designs. The most exciting part of the project for the students was the target: their teacher, Will Dunn.

"This project was a ton of fun. I wish more school projects could be fun like this one was," said YACS student Matthew Holzer.

"The projects turned out great,'' Dunn said. "The only detail that could have been better was the weather."