• CCB Science pages 96 - 101



  • Identify limiting factors that affect carrying capacity

  • Identify different kinds of relationships within a habitat

  • Explain the relationship between equilibrium and carrying capacity

Key Concept

  • A habitat’s limited ability to support the living things within it is called its carrying capacity. Carrying capacity is shaped by limiting factors in the environment.


Evidence-Based Reading

  • Forms of a Word: Write the word habitat on the board. Next to the word, write: from the Latin word ‘habitare’, meaning it dwells or lives. Ask a volunteer to define the term as it is used in the lesson. Next, write the following words on the board: habit, habitable, habitual, habitation, inhabitant, and habilitate. Read the words aloud. Remind students of the origins of the word habitat, and then ask them to use that meaning to define the terms you listed. Offer examples of sentences using the related words to guide student understanding. Ask students to explain how knowing a word’s history can help them define related words.

21st Century Skill

  • Workplace Connection, Wildlife Management: Ask a volunteer to read the text aloud. Then ask students to explain the responsibilities of a wildlife manager. Remind students that some managers may mark and track wildlife movement in an ecosystem. Encourage students to discuss what managers can learn about animals by monitoring their movement.

Writing Practice

  • Work with students to identify possible areas in the community where humans are putting pressure on environmental resources or species. Then select one of the areas and ask students to apply the concepts of limiting factors and carrying capacity to describe what might be happening there.

Before Lesson

This lesson requires students to explain the concept of carrying capacity. To determine their readiness for the lesson, write the words serving size on the board, and ask students to describe where and when they have seen those words. Ask students to imagine that they have opened a package containing two serving sizes, but they must share the contents among four people. Have students explain some of the possible consequences of having fewer servings than are needed.


To understand the concept of carrying capacity, students need to fully grasp the concept of an ecosystem and of habitats of varying sizes within ecosystems. A habitat is the place where a population lives. An ecosystem is a collection of populations of different plants and animals that occupy and interact within a physical environment, either on land or water. The largest terrestrial ecosystems, or biomes, include different kinds of grasslands, deserts, forests, and alpine or mountain biomes. Ask students to identify the largest ecosystem in which they live. For example, the town or city in which students live may be on a prairie or in the foothills of a mountain ecosystem. Ask students to describe the physical environment and to name some of the organisms that live in the ecosystem.

Guided Practice

  • Carrying Capacity
    • Relationships in a Habitat
  • Reindeer on the Pribilof Islands
  • Dietary Diversity

Core Skill

Cite Textual Evidence: Ask students to read the text and identify supporting evidence before discussing changes to the moose population as a class. Invite students to share their answers and the evidence they used to construct those answers. If students provide answers without citing evidence, have them skim the text again, and if necessary, revise their answers.

Understand Text: Before students do the activity, ask them to give examples of jargon associated with math, history, art, or any other area of study. Begin by providing a few common examples from a particular discipline, such as equation, variable, area, perimeter, and volume from mathematics. Then have students read the text before inviting them to describe what they would do first in an attempt to parse the text to define the jargon. Then have volunteers restate the text in their own words.


Explain a Diagram: Encourage students to describe the diagram of the sea otter’s dietary diversity in their own words. Explain any words in the diagram that are unfamiliar to students while drawing their attention to the pictures. Cover one or more of the foods in the diagram and ask students to explain the consequences of removing these organisms from sea otters’ diets.

Sketch Your Plan: Provide graph paper and drawing materials. Have students use the paper and materials to develop the ideas they presented in Write to Learn. Ask students to draw the area they wrote about and show how organisms are affected by human activity. Encourage students to share and compare their work.

Lesson Review