Beneath Earth’s crust lies a layer of hot, molten rock. It can make its way to the surface, where it erupts from volcanoes. Lava flows down the sides of volcanoes, while gases and ash thrown into the air form dense, mushroom-shaped clouds.

“I Want to Read! Level 4” is for advanced readers. The vocabulary is specialized, the illustrations offer less support, and the diagrams, maps, and charts are complex. More abstract concepts are also covered.