Check out this wicked cool science experiment we recently did. It's called Bobbing Raisins or Diving Raisins. You put about 2 T. of baking soda in a tall, clear glass. Then you SLOWLY pour in white vinegar. You can pour it in fast and get that volcano effect and amaze the little tots; just put a towel under it. When it's as full as you want it to be, pop in a bunch of raisins and watch them sink. Then come to the top. Then sink again. It's cool. Something about releasing gas and then going back to the bottom. I told the boys it's like the raisins swim to the top to fart, then sink to the bottom to get more gas. Hey, when you're dealing with boys and small tots, you have to be creative! Have fun!