Habitats and Change introduces Grade 3 students to real-world examples and fundamental concepts that will be explored in greater depth in later grades. Students learn about the observable effects of change that affect habitats, describe and predict patterns of changes, and explore possible solutions to harmful changes to habitats. In this Reader, students learn one of the guiding principles in biology that helps account for the amazing diversity of life forms on Earth: living things look and behave as they do because they are adapted to their environments.

When reading Habitats and Change, students become aware that a fire, a flood, rising temperatures, or the arrival of a new predator can change a habitat. When change occurs, organisms may find that adaptations are no longer helpful. Some members of a population may die. Environmental change may also allow new organisms to thrive. Evidence from the past supports the idea that living things adapt to changes in their environment. The fossil record shows that species that lived for millions of years went extinct when some aspect of the environment changed, and their traits no longer allowed them to survive while other organisms managed to survive.