This nonfiction reading unit (level X) explains that every ecosystem has a unique food web. Students learn how energy flows through different parts of an ecosystem and how different parts of an ecosystem are connected. The unit contains teacher support pages, a reading selection with supporting illustrations, and activities to guide students in close reading of the text. Students also gain practice applying content and academic vocabulary. The unit concludes with a lesson exploring text structure (Cause and Effect) and a text-based writing activity.