We did one in the 4th grade we took a small cone that you use on the playground and put brown,grey,red play dough on it placed a plastic cup inside of cone put it on a piece of card board colored water and rocks around it and we put baking soda in the cup, red food coloring and poured vinegar in the top to make it exployed. Little messy. And Micheals use to have a kit. or use soda and a mintoes candy to expoled