When I was ten, I determined that I would hold a summer school for my younger sisters, so that none of us would lose our mental acuity in the languid vacation months. Science experiments, reading, math tests were all forming in my mind. After three days (hours) of preparing, I lost interest and went to the beach without ever having taught a lesson. But if I had had the resources of today (high-speed internet, Pinterest, thousands and thousands of mom and teacher bloggers), I might have stuck with it for a lot longer, because the experiments I found today are awesome! 

Sharpie Tie-Dye 

Watch crystals form in various colors over the course of a week with this tutorial from Brandy's Crafts, and eat the results while talking about saturation and condensation. More details about the exact science can be found at Wonder time. 

Make a lava lamp with household items, like this one from Bird and Little Bird, and watch the carbon dioxide bubbles from Alka-seltzer make colored vegetable oil whirl around like the classic seventies lamp. 

Gak

CD Hovercraft