You'll probably ask what did we create for our science fair.
We made a volcano... but, why did we do a simple volcano? It's easy, well... volcanos are not a simple thing, I mean, they are not just a rupture in the surface which allows hot lava and volcanic ashes.
Generally, they're formed at the boundaries of the tecntonic plates, inside has open fires where the lava rises from the magma chamber, a reservoir where lava accumulates.
So, what we did for our science fair was a little volcano which would represent a real volcano eruption so people could understand better the process it requires.