summer of science fun: fizzy fountain

I stole most of these science experiments from the ones on my friend, Brittany's, blog, which she in turn got from books and internet sites and such.  This one was similar to making a lava lamp, and the kids loved it!
Fill a bottle 3/4 full with cooking oil, and fill the rest of the way with water.  Add several drops of different colors of food coloring.  Break up some alka seltzer tablets and add a few pieces at a time and watch the sciencey (that's a word, right?) fun unfold!