A pinhole camera you can really get into.
Trace your shadow, then watch it change.
Experiment with cardboard tubes of different lengths to see how far you can blow a marshmallow.
Use a soda straw to make sounds resonate.
Create your own personal sound system with a coat hanger and a string.
Build a paper-pencil-pin phonograph.
Rub a balloon on your head, then watch a soda can race across the floor or a table.
Learn about water chemistry, phase changes, and density.
Changes in fluid pressure affect the buoyancy of a Cartesian diver made from a condiment packet.
Two hinged mirrors create a kaleidoscope that shows multiple images of an object.