The Catapult Project.

...I wrote this one down as science and math in the portfolio I have to keep of Jonah's "school assignments".

We launched various and sundry objects for hours, adjusting the coils, changing the angles...  it is now a permanent fixture in our living room.  I suggest it for all living rooms.  It comes in extremely handy in moments of frustration.  There really is nothing quit like launching something across a room in your house with the aid of levers to lower the blood pressure.