Does anyone know how to make the "lava" in an erupting volcano science project, thicker and more life-like?

Answer 1

Ammonium dichromate (NH4)2Cr2O7) is a red-orange crystal that looks like lava. When it is lit, it spews out greenish gray particles. It is the best approximation I have found.
Have someone build a paper mache volcano. Have a small can built into the top.

Answer 2

experiment with different ratios of vinegar and baking soda. You could also add various food colorings for effect. When i made mine in elementary school, i made the top container that held the solution out of a small glass jar, and put a red light bulb inside the volcano under the jar, causing it to glow red. it looked really cool.