Early Elementary:

Engineering Toothpaste -- make your own toothpaste with chemicals from nature!
If I Have Acid In My Stomach - Why Don't I Melt? -- the answer is "snot" what you think!

Later Elementary:

Make Plastic Out of Milk -- and you thought it could only be made out of oil based products!

Novocain -- examining pain killers and the nerve's response to it.
Where Does Jell-O Really Come From -- is it really made from cow hooves?

Middle School:

Make Your Own Paint -- use red bricks and eggs for your next paint project!
Lemon Power -- make a battery from a lemon!
Playing with Polymers -- use glue and borax to make a "Silly Putty" look-alike!

High School:

Antacid Tablet Race -- understanding rocket propellants and fuel by investigating Rolaids and Tums Liquid Nitrogen Fun -- dry ice experiments!