STC™ Program - Science and Technology Concepts STC BOOKS™ are colorful 64-page readers with research-based science content, giving teachers an ideal way to integrate science instruction during guided, independent, or take-home reading. Teachers use STC™ science curriculum materials to enhance elementary classrooms, increase student test scores, and meet national and state educational standards.

Grades 4-5. This reader gets students thinking of ecosystems-what they are, what threatens them, and what scientists and others are doing to keep them in balance. The book's first section introduces students to basic concepts about ecosystems, from a brief ecological vocabulary lesson to information about the interrelationships of animals with the land and plants in their range. One story presents the theory that a global catastrophe led to the extinction of dinosaurs. Other readings discuss threats to Earth's ecosystems and ways people can minimize those threats. The final section of the book relates the stories of 3 environmental pioneers: Henry David Thoreau, John Muir, and Rachel Carson.