Make a volcano out of paper mache' or plaster of paris around a 1 liter plastic soft drink bottle placed on a board. For effect, our kids paint the volcano violent colors. Take it outside when it's good and dry. Mix one tablespoon of dish soap (ya'll call it washing up liquid, no?) with one tablespoon of baking soda and some red food coloring. Pour it into the bottle. Then pour in about 1/4 cup of vinegar and hurry back several steps! Kids love it, but it's a mess if you don't put it outside... They love to use their imaginations in painting and forming the volcano as well as putting little trees on the sides...