Everywhere on earth there are rocks. Some rocks are very hard; other rocks are softer. Not all rocks are the same.

Rocks come in all sizes, from great big boulders to tiny pebbles. Even grains of sand are teeny tiny particles of rock.

Rocks change over time. Some rocks tell stories. Scientists who study rocks are called geologists.

Fossils are found in some rocks. They give scientists information about plants and animals that lived millions of years ago.

Crumbled rocks mixed with dead plants and water make soil. Water can make rocks slowly change and wear away.

The earth is a great ball of rock. Sometimes rocks melt when they get very, very, very hot. Volcanoes form when rock underneath the earth becomes very hot and melts. The melted rock is called lava.

Rocks are used for building walls and roads. Rocks, sand, and water are mixed together to make cement. Cement is used to build our houses and schools.