V is for Volcano. Using a large triangle for a peak, and two diamonds to represent lava, a volcano can be constructed. Most children might not need a lot of work to build their understanding of volcanoes, but it is spectacular and mesmerizing to watch videos of magma emerging from volcanoes. My students and I both enjoy it immensely:
Model volcanoes from clay are always a fun project too. You can add baking soda and vinegar for a bang.