This nonfiction reading unit (level Y) focuses on genetic traits. Students learn that all animals receive genetic traits from their parents, and these traits help the animals survive in their natural habitats. 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 (Main Idea and Details) and a text-based writing activity.