This engaging 250-word reading passage introduces fourth-grade students to the essential internal structures that keep animals alive, aligned with NGSS standard 4-LS1-1 and Disciplinary Core Idea LS1.A. Students explore how the skeleton provides support and protection, the heart pumps blood throughout the body, lungs or gills obtain oxygen, the stomach and intestines digest food for energy, and the brain controls all body functions. The passage emphasizes that these internal structures are essential for survival and that different animals have different versions of these structures depending on their needs and environment. Audio-integrated features support diverse learners, while age-appropriate language and concrete examples make complex biological concepts accessible to fourth graders. The passage includes bolded vocabulary terms with immediate definitions, helping students build scientific literacy. Differentiated versions ensure all students can access the same core science concepts. Companion activities include comprehension questions, writing prompts, and graphic organizers that reinforce understanding of structure-function relationships in living organisms.
Written by Workybooks TeamPublished by Workybooks
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These internal structures help animals survive.
Animals have many parts inside their bodies that work together to keep them alive. These parts are called internal structures—body parts found inside an animal. Each internal structure has a special job, and all of them must work together for the animal to survive.
The skeleton is a framework of bones that supports the body and protects important organs. Without a skeleton, your body would be like a tent without poles—it would collapse! The heart is a muscle that pumps blood through the body, delivering oxygen and nutrients to every cell. Think of the heart as a delivery truck that never stops working.
Animals need oxygen to survive. Lungs are organs that take in oxygen from air, while gills are organs that take oxygen from water. Fish have gills because they live underwater, but humans and many other animals have lungs because they breathe air.
The stomach and intestines work together to digest food. The stomach breaks down food into smaller pieces, and the intestines absorb nutrients the body needs for energy and growth. Finally, the brain controls everything. It sends signals to all body parts, telling them what to do and when to do it.
Different animals have different versions of these structures depending on where they live and what they need. Without any one of these internal structures, an animal could not survive.
Interesting Fact: A giraffe's heart weighs about 25 pounds and must pump blood all the way up its long neck to reach its brain!
What are internal structures?
Body parts found inside an animalBody parts found outside an animalOnly bones in the bodyParts that animals don't need
What does the skeleton do?
Pumps blood through the bodySupports body and protects organsDigests food for energyControls all body parts
Which organ pumps blood through the body?
The brainThe stomachThe heartThe lungs
Why do fish have gills?
To digest food underwaterTo pump blood fasterTo take oxygen from waterTo control their movements
What do intestines do?
Break down food into piecesAbsorb nutrients from foodPump blood to cellsSend signals to body parts
Which structure controls all body parts?
The heartThe stomachThe skeletonThe brain
Animals can survive without internal structures.
TrueFalse
What does digest mean in the passage?
To pump blood through vesselsTo break down food for nutrientsTo breathe oxygen from airTo send signals to organs