Grade 4 · Science · Lesson 25

Digestive and respiratory systems

Your body needs nutrients from food and oxygen from air to produce energy. Two body systems work together to supply these needs: the digestive system breaks down food, and the respiratory system takes in oxygen. Understanding both systems helps you make healthy choices every day.

What this lesson teaches

1Describe the main organs of the digestive system and their functions
2Explain how food is broken down and nutrients are absorbed
3Identify the main parts of the respiratory system
4Explain how breathing brings oxygen into the body

🔒 Member-only content

Unlock the full lesson

Subscribe to access the complete mini-lesson, guided practice, interactive exercises, and printable PDF for this lesson — plus all 1,680 lessons across grades 1–6.

See membership plans Try a free lesson first

The first lesson of every subject is free — no account required.