In the leveled reader Protozoa, fundamental science concepts of biology are explained through easily understood text and colorful illustrations and photographs. Young readers discover that protozoa are organisms too small to be seen with only the eyes. Protozoa were discovered by Anton van Leeuwenhoek when he looked at pond water with a microscope, a tool that makes tiny things look bigger. There are thousands of protozoa of different shapes and sizes that live in water. Euglena, paramecia, and amoebas are described and illustrated. A euglena moves by twirling a long tail called a flagellum, uses sunlight to make its own food, and has an eyespot that can detect light. A paramecium swims by wiggling tiny hairs called cilia and also uses the cilia to sweep food into its mouth. An amoeba crawls and eats by using "false feet."

A pronunciation guide of scientific terms is included. 24 pages with colorful illustrations and microscopic photographs. Reading Level 1-3, Interest Level 2-5. Lexile measure 460L.