• CCB Science pages 24 - 29



  • Recognize the organs and processes of the digestive, excretory, circulatory, and respiratory systems

  • Explain how these systems work together to provide the body’s cells with energy and remove cellular wastes

Key Concept

  • To carry out life activities, cells require food and oxygen. They also produce wastes. Each system plays a role in delivering the materials that cells need and carrying away wastes they make.


Tier 3 excretory system
respiratory system

Evidence-Based Reading

  • Words as Context Clues: Invite students to work with a partner to reread the text on this page. Model questions that students can ask themselves while reading, such as: What is this paragraph about? How is this paragraph organized? What are the important ideas? Do they form a pattern? After reading, have students underline words that serve as context clues. Point out that the words in, down, into, there, across carries, passes, and leave indicate location and movement from place to place. Students will notice that the text follows the sequence of food as it moves through the body. Help students recognize that the writer has placed ideas in the order that events happen. The text therefore follows a time-order pattern of organization.

21st Century Skill

  • Information Literacy: Have students read the text and then explain the meaning of the terms reliable and reputable in their own words. Invite students to give specific examples of how they can assess the reliability of a website and the articles found there. A reliable article should list an author, along with the author’s credentials (information about their qualifications, degree, and employer). Remind students to look for the purpose of a website. For example, is the site selling a product? If so, information at the site might be biased.

Writing Practice

  • Answers will vary, depending on which diagram the student selects. Remind students to use information from both the text and the diagram when writing their paragraphs.

Before Lesson

Determine students’ readiness for learning about the digestive, respiratory, excretory, and circulatory systems by asking volunteers to name one organ from each system. Provide assistance, if necessary. Ask students to brainstorm aloud about what they think the function of each organ is. Guide students to recognize that every organ plays a role in two vital tasks: providing cells with energy and removing cellular waste.


Tell students that the levels of organization in the body include cells, tissues, organs, and body systems. Just as every cell in the body is interdependent, so are the body systems. Communication and teamwork among these systems make it possible for the body to do jobs such as pumping blood and getting rid of wastes. Stress interdependence as students read.

Guided Practice

  • The Digestive System
  • Integrate Text and Visuals
  • The Excretory System
  • The Circulatory System
  • The Heart
  • The Respiratory System

Core Skill

Determine Central Ideas: As a class, look for the central idea of the first paragraph of “The Excretory System.” Encourage students to read this paragraph to find one or more words (such as remove, waste, or filters) that suggest the function of the excretory system.

Integrate Text and Visuals: Read the text with students. Encourage students to discuss how integrating text and visuals helps them make meaning of text and understand complex concepts or processes.


Practice Pronunciation: Select words or phrases that students might find difficult or that do not transfer well from their first languages. Model intonation and emphasize the stressed syllable in multisyllabic words. Have students repeat the words.

Investigate Body Systems: Have small groups of students work together to find additional details about a body system. They might research the system in more detail, identify diseases associated with the system, and determine the cause and effects of each disease. In their research, students should cite evidence regarding the cause of each disease and summarize possible treatments.

Lesson Review