Well, I do some volunteer work with APEGGA (Association of Proffesional Engineers, Geologists and Geophysicists of Alberta) and every year we host a “Get interested in Science” science fair for grades 4-6 at a local school. Most of them are pretty easy experiments and kids get a kick out of them.
A couple of my favorites (and are pretty easy):
How many books can you stack on 6 eggs (or however many) until they break? This one always gets a crowd.
Paper airplanes are always good as well for showing some of the physics of flight and they’re fun to build.
I did one this year that demonstrated differences in pressure. I got 2 empty 2 Liter pop bottles. I filled 1 with water and put a 1/2 full “dropper” thingamajig in it. The empty one then screwed onto the top of the full one with a female/female threaded coupling for pop bottles. Normally, the 1/2 full of water plastic dropper thingy would float at the top of the bottle with the water, but when you squeezed the empty pop bottle it would sink.
Neato!
For added fun, you can try to shape a hook or something on the bottom of the dropper things (submarine) and try to hook it onto another sunken hook at the bottom of the bottle.
Bridges made out of toothpicks and/or popsicle sticks are good too. See who can make the strongest bridge from 6-10-15 sticks and then see how many marbles/rocks whatver you can stack on them before they break.
Just a few ideas.
