Love this interactive science site! My 3rd and 6th grader have learned about everything from the parts of a flower, to electrical currents and melting points. The games are really engaging; this has been a great supplement to our homeschooling.
Bottle Ecosystem, This is the most awesome class idea to teach ecosystems! Its self contained and you can observe the activity for the rest of the year. No mess no fuss and all of this cost about 17 dollars.