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23.3: Lesson 23.2: Early Space Exploration

Difficulty Level: At Grade Created by: CK-12
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Key Concepts

  • Rockets
  • Satellites
  • The Space Race
  • Reaching the moon
  • Exploring other planets

Lesson Objectives

  • Explain how a rocket works.
  • Describe different types of satellites.
  • Outline major events in early space exploration, including the Space Race.

Lesson Vocabulary

  • orbit: circular or elliptical path of one object around another
  • rocket: vehicle propelled by gas particles flying out one end of it at high speed
  • satellite: natural or human-made object that orbits another object
  • space probe: spacecraft that is sent without a crew to collect data by flying near or landing on a distant object in space
  • Space Race: competition during the Cold War (1945–1990) between the United States and the Soviet Union, in which each nation strove to have the best space technology
  • thrust: forward force produced by gases flying out of the end of a rocket

Teaching Strategies

Introducing the Lesson

Ask if any students have ever wanted to be astronauts. Generate a discussion of this exciting career by asking follow-up questions such as:

  • Why would you want to be an astronaut?
  • What do you think it would be like to be an astronaut?
  • Where would you want to go if you were an astronaut?

Encourage a diversity of responses from multiple students. Then tell students they will learn about astronauts and space travel when they read this lesson and the next.

Building Science Skills

Students can apply Newton’s third law of motion and basic rocket science to build and launch a model rocket powered by an antacid tablet reacting with water. Detailed instructions are provided on pages 58–61 of the following document. The process of completing the project will help students understand the basic science behind rockets.


Differentiated Instruction

Suggest that students make a simple timeline of space exploration, starting with 1957 (Sputnik 1) in this lesson and ending with the present time in the next lesson. This will help students focus on the most important events in space exploration and their correct sequence.


Ask students with a strong interest in history to learn more about the Cold War context of the Space Race and the effects of the space race on U.S. citizens. Then have the students teach the topic to the rest of the class. The URLs below are some useful sources they might consult.



Science Inquiry

Students can use microsets of NASA satellite data to study Earth’s climate zones, learn how to interpret satellite images, and gain an appreciation of the value of using satellites to gather data about Earth. The URL below provides a lesson plan for the study. The Web site includes instructions for accessing the satellite data. The lesson plan itself includes background information, the procedure, a set of questions, ideas for extension, and useful links. Teacher notes are also available.


Common Misconceptions

A common misconception is that satellites remain in orbit because they have “escaped Earth's gravity.” Of course, this is false, because gravity still exists in space. Explain to students that if it weren’t for gravity, satellites would fly off into space rather than stay in orbit. The only thing that keeps them from falling back to Earth because of gravity is their horizontal velocity. Because of this velocity, they keep falling “over the horizon” rather than crashing into Earth’s surface. In short, speed, not lack of gravity, keeps satellites up in space.

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 23.2 Quiz in CK–12 MS Earth Science Assessments.

Points to Consider

The Space Race and the USA’s desire to get to the moon brought about many advances in science and technology. Can you think of any challenges we face today that are, could be, or should be a focus of science and technology?

If you were in charge of NASA, what new goals would you set for space exploration?

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