How Fish Gills Work

This engaging 250-word reading passage introduces fourth-grade students to the concept of fish gills and how they function as respiratory structures. Aligned with NGSS 4-LS1-1 and the Disciplinary Core Idea LS1.A (Structure and Function), the passage explains that fish do not have lungs because they live in water. Instead, they possess gills—internal structures located on the sides of their heads that extract dissolved oxygen from water. Students learn how water flows over the gills, allowing oxygen to pass into the blood while carbon dioxide is released. The passage emphasizes that gills solve the same survival need as lungs but are specially adapted for an aquatic environment. This audio-integrated resource includes a simplified differentiated version for struggling readers, complete Spanish translations of both passages, a comprehensive glossary of key terms, multiple-choice questions testing recall and application, writing activities with suggested answers, and graphic organizers in table format. The content builds foundational understanding of how different animals have different structures that serve similar functions, preparing students for hands-on investigations and deeper discussions about animal adaptations and survival needs in various environments.