The English Scientist, Neil Downie, has written three volumes of Saturday Science Projects. His designs are remarkably original and thoughtful., explaining the math and science of every project.

Looking at wave forms at different speeds and the effect of weight, air friction and gravity. As the speed changes, see the different number of waves traveling around the edge of the cloth. Note whether the speed of the wave is the same on the inside and outside. What is the shape of the wave? So much to learn. Thoroughly enjoyable to do.