Many mammals, insects, and other animals are easily recognizable. However, there are other creatures that are less well known, such as protozoa, which are single-celled living things that are neither plants nor animals. These tiny organisms can only be seen by looking through a microscope. They live in various habitats and even inside animals. This age-appropriate and well-researched text simplifies this complex biology topic to make it more easily understandable for young readers. Detailed graphic organizers, informational diagrams, engaging fact boxes, and vibrant, full-color photographs enhance this essential science curriculum topic.