We made a volcano the other day. I've never done a "science" volcano, and I really didn't know what I was doing, but it turned out well. I mixed up some flour (unnecessary ingredient), baking soda, and vinegar for it. First we put the baking soda in our volcano (made from a 2L pop bottle and covered with tin foil for structural purposes), and then I dumped in the vinegar. The kids loved making the volcano "angry."