Study animal classification and the difference between warm- and cold-blooded animals. Learn about the structures and functions of plant and animal cells. Explore biotic and abiotic ecosystems. Reading passages, answer keys, and tests. 60 pages plus 6 mini posters. Grades 5-8; Reading Level 3-4. Ecology & The Environment Big Book includes all 3 books combined. 170 pages, 18 mini posters.