Mechanical Weathering Lesson Plan

Instructor: Sharon Linde

Sharon has a Masters of Science in Mathematics

Teach your students about mechanical weathering with this lesson plan. Students will watch a video lesson defining mechanical weathering and explaining the process and types. Hands-on activities, discussion questions and a quiz round out this lesson plan to make concepts stick.

Learning Objectives

After this lesson, students will be able to:

  • define mechanical weathering
  • explain the process of mechanical weathering
  • describe the types of mechanical weathering


1 hour for lesson, plus time for experiment


  • Colored sidewalk chalk
  • Salt
  • Clear plastic cups
  • Plastic spoons
  • Plaster
  • Paper towels
  • Water
  • Bean seeds (soak in water the night before class)

Key Vocabulary

  • Mechanical weathering
  • Thermal expansion
  • Grus
  • Frost shattering
  • Abrasion

Curriculum Standards

  • CCSS.ELA-Literacy.RST.6-8.3

Follow precisely a multistep procedure when carrying out experiments, taking measurements, or performing technical tasks.

  • CCSS.ELA-Literacy.RST.6-8.4

Determine the meaning of symbols, key terms, and other domain-specific words and phrases as they are used in a specific scientific or technical context relevant to grades 6-8 texts and topics.


  • Divide students into small groups and give them each a piece of sidewalk chalk, salt and a cup.
  • Instruct students to fill their cups ¾ of the way full with salt, then hold the end of the sidewalk chalk and stir the majority of the chalk into the salt mixture at a constant rate for five minutes. Have them take turns stirring.
  • Instruct students not stirring to make a prediction about what will happen to the chalk.
  • After five minutes have children pull the chalk out of the salt cup and set it on a paper towel to observe. Ask:
    • What happened to the chalk?
    • Why do you think this happened?
    • Were your predictions correct? Why did you make these predictions?
  • Set the materials aside and tell students they will learn more about what happened to the chalk in today's lesson.
  • Write 'Mechanical Weathering' on the board and start the video Mechanical Weathering: Definition, Process, Types & Examples.
  • Pause at 1:25 to define 'mechanical weathering' and ask:
    • How was our experiment an example of mechanical weathering?
  • Resume the lesson, pausing to define 'thermal expansion,' 'frost shattering,' 'plant activity' and 'abrasion.'
  • Pause at 5:30 and have students make a four-column chart with each of the types of mechanical weathering. Instruct them to write a definition and example under each category on their chart.
  • When students are finished, review charts for accuracy, then discuss:
    • How does temperature fluctuation affect rocks?
    • What impact can water have on rocks?
    • How is abrasion different than the other types of weathering?
  • Play the remainder of the video and have students take the quiz together.

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