PBS site offers an experiment kids can do at home to see how carbon dioxide can put out burning candles.

This article explains how helium is able to keep balloons afloat in the air. Compares them to how hot air balloons work. Includes a video, and some activities to try for testing the principles being discussed.

An easy to do activity that investigates Bernoulli's principle. The activity is presented in lesson plan format that meets NSES standards.

Great animations showing how sound is produced.