Dear Katie, The Volcano is a Girl by Jean Craighead George (illustrated by Daniel Powers; Hyperion, 1998) is the story about a grandmother and a granddaughter on vacation in Hawaii. They tour a volcano, and while Katie insists that the volcano is Pele (a goddess) her grandmother disagrees and explains how volcanoes form because cracks between plates of the earth ooze magma, forming an island.

I love how the folklore is woven into a storyline. It is highly readable and also educational. This would a great introduction to a lesson about earth science, especially volcanoes.