Son has a science project - science fair actually - he is almost 9 and picked "why do boats float" based on experiments done in the bathtub. Why indeed. Attempting to explain displacement, buoyancy and density were getting me nothing but glazed stares and worse- so I googled "why do boats float" and got lots of good simple explanations - including our favorite involving equal pieces of aluminum foil formed into different shapes (compressed ball - doesn't float, "boat" - does) . So I think we may be OK here, although when I described what a "hypothesis" was, I got "but thats just a guess!?" -  Yes, exactly, just a guess - an educated guess perhaps, but thats it! A Guess. He was not really buying this, so I had to "google" that as well ( you know because if its on "Wikipedia" it may be more believable than if mom says it. Whatever. It's all about Archimedes in the bathtub.

Trebuchets - for some reason, I really like these - probably ever since that episode of Northern Exposure where they were throwing pianos and coffins, etc.  A few years back, I bought my husband a "table top" version (good for launching things at your cubicle mates - although we are in hard offices) and he wanted to know "where on earth did you find this" - why - at "Trebuchet.com" (Dedicated to the art of hurling) Got to love that.  

 They sell the "Warwolf"  - which is a "backyard"  Trebuchet . At 1/10 scale, This is a working model capable of tossing 1/4 lb up to 1 pound** missiles over 100 feet! Good for getting the neighbors noisy dog. (stop, I love dogs, really, I do. ) 

Speaking of Trebuchets and Pirates.....We go to a great winery  - "Twisted Oak" in Murphy's (Gold Country of California) which hosts an annual party that involves pirates, wine and trebuchets.