Over the last couple of weeks, we've been studying Venus in science using Apologia's Exploring Creation with Astronomy text. Each lesson incorporates a mid-lesson activity (usually an experiment). This unit's mid-lesson activity was to make lava using some basic household supplies.
We used butter to represent rock. When heated, the rock melted into molten rock (or lava once it's spewed from a volcano). After the volcano erupts, lava rolls down the mountain, destroying everything in it's path and ultimately cools and rehardens into rock.