A piece of silk is smooth. Tree bark is rough. Why are some objects smooth and others rough? Find out in this series about materials and their properties. Infor

The rocks you see everyday can be grouped into different types, like igneous, sedimentary, or metamorphic. Some rocks are actually minerals, and you can even fi

Learn how to tell if something is stiff or bendable and which materials have these properties.

Discusses the sense of touch and how it affects the body.

Young readers learn some surface that are smooth, and some that are rough.