Grade 3 Unit 3 (English)

Ecosystems Living things depend on one another. They also depend on nonliving things, such as sunlight. Earth has many different kinds of ecosystems. Different organisms live in different parts of an ecosystem. Living things get food, water, and shelter from their habitats. Many different habitats make up an ecosystem. Interactions in Ecosystems The different parts of an ecosystem interact. All of the parts depend on and affect one another. For example, animals depend on plants for food and shelter. Squirrels get acorns from trees to eat and gather branches to make nests in trees. Squirrels can change and affect how trees grow. Trees and other plants give off oxygen that animals need to survive. Living things also depend on and affect nonliving things in an ecosystem. The grass on a meadow could not grow without air, water, sunlight, nutrients, and soil. When chipmunks and rabbits dig in the ground, they break up rocks, which helps form the soil. VOCABULARY Seeds blow onto bare ground. The environment changes as plants take in water and nutrients. As more plants grow, animals move in to the environment. They use the plants for food and shelter. Look for these words as you read: invasive species Copyright © McGraw-Hill Education NPS Photo/Cookie Ballou 74 EXPLAIN Module: Change the Environment