This kid (and his father, you know his dad helped) built this freaking sweet air car.

All that and catchy music. It also looks like it uses a fair amount of bicycle parts, making it even cooler. I wish I had learned how to weld in fifth grade. According to the Youtube page it can go about half a mile and goes about 9mph, not going to change the world, but still pretty awesome for a fifth grader. My science fair project in fifth grade was a stupid volcano made with vinegar and baking soda. To my credit it did have a cut away model showing the magma chamber, but still it was no air car.