Rocks introduces fundamental scientific concepts in geology. Magma is molten material inside Earth that forms rocks when cooled. The three main types of rock are igneous, sedimentary, and metamorphic. Igneous rocks come from magma that cools inside Earth; sedimentary rocks are formed from bits of rock left behind by wind and water and are often layered; metamorphic rocks are formed from other rocks that have been changed by heat and being squeezed within the Earth. Geologists look at the features of rocks and do tests to determine the type of rock and how it was formed. A pronunciation guide of scientific terms is included. 24 pages filled with engaging, colorful illustrations. Reading Level 1-3, Interest Level 2-5.