Lets spend a day making gas.
First:
vinegar and baking soda. Add 20ml Vinegar to 20mL water to 1 scoop baking soda. Drop in 3 raisins. Explain the phenomenon. What gas is produced? How to test for it?
Second:
Acid and metal. Zinc chips and HCl. Capture in a balloon or test tube. How do we test?
http://chemistry.about.com/od/makechemicalsyourself/a/How-To-Make-Hydrogen-Gas.htm
For homework, make your own blog post about what you did.