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18.4: Lesson 18.3: The Human Population

Difficulty Level: At Grade Created by: CK-12

Key Concepts

  • Population growth rate and carrying capacity
  • Human population growth
  • Human population and the environment

Lesson Objectives

  • Explain how populations grow.
  • Describe how the human population has grown.
  • State how the human population affects the environment.

Lesson Vocabulary

  • carrying capacity: maximum population of a species that can be supported by its environment
  • demographic transition: changes in population birth, death, and growth rates that first occurred in Europe and North America beginning around the time of the industrial revolution
  • green revolution: revolution in agriculture that began in the mid-1900s and increased food production with the use of new methods and products such as chemicals to control weeds
  • population growth rate (r): speed at which a population grows
  • sustainable development: using resources in such a way that people will have what they need but the resources will not run out and the planet will not be harmed

Teaching Strategies

Introducing the Lesson

Introduce the human population by showing students a worldwide human population clock at one of the following URLs. It will show them how quickly the human population is growing. Tell students they will learn why there are so many people and why the human population is growing so rapidly when they read this lesson.


Demonstrate population growth with the video at the following URL. The video will help students visualize how changing birth and death rates affected human population growth in different areas of the world over the past 1000 years.


Building Science Skills

With the hands-on activity at the URL below, students can experience the changing pace of human population growth by simulating Earth’s population growth over the last 500 years. In addition to the activity procedure and materials, the PDF document includes discussion questions and a follow-up activity.


Differentiated Instruction

Have students make a KWL chart for the lesson. It will help them recall anything they may already know about the human population and focus their reading on what they would like to know. Tell them to make a three-column chart with the headings Know, Want to Know, and Learned. They should fill in the Know and Want to Know columns before they read the lesson and the Learned column after they read the lesson. Ask students what they think is the most important thing they learned from the lesson.


Suggest that interested students do a Web quest to find answers to the following questions:

  1. Who was Thomas Malthus?
  2. What did Malthus write about populations?
  3. How did Malthus’ writings influence Darwin and his theory of evolution?
  4. Do Malthus’ ideas apply to the human population? Why or why not?

Science Inquiry

Use the activity at the URL below so students can analyze the way the human population has affected the planet. In the activity, students will learn about the Human Footprint data set, analyze a map showing where and to what extent humans have influenced Earth, and participate in a class discussion. The URL provides all of the materials and instructions needed for the activity.


Common Misconceptions

There are many misconceptions about the human population, its growth rate, and the causes and consequences of human overpopulation. The article at the following URL discusses ten of these misconceptions. Discuss some or all of the misconceptions with your students. Explain how the misconceptions originated as well as why they are incorrect.


Reinforce and Review

Lesson Worksheets

Copy and distribute the lesson worksheets in the CK-12 Earth Science for Middle School Workbook. Ask students to complete the worksheets alone or in pairs to reinforce lesson content.

Lesson Review Questions

Have students answer the Review Questions listed at the end of the lesson in the FlexBook® student edition.

Lesson Quiz

Check students’ mastery of the lesson with Lesson 18.3 Quiz in CK-12 Earth Science for Middle School Quizzes and Tests.

Points to Consider

In this chapter, you read how humans are harming the environment. For example, we are quickly using up many natural resources. Soil is one of our most precious natural resources. It takes a very long time to form. But it can be washed away in a single rainstorm. How do you think human actions are affecting the soil?

What can people do to protect this important resource?

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