Physical Weathering Lesson Plan

Instructor: Joanne Abramson

Joanne has taught middle school and high school science for more than ten years and has a master's degree in education.

In this lesson plan, secondary students take a deeper look at physical weathering. Using a short text lesson, oral and written reflections, demonstrations and hands-on lab activities, students investigate different types of mechanical weathering.

Learning Objectives

By the end of the lesson, students will be able to:

  • define the term 'physical weathering'
  • describe several types of physical weathering
  • recognize the effects of physical weathering


1-1.5 hours

1 day or weeks to check results

Curriculum Standards


Follow precisely a complex multistep procedure when carrying out experiments, taking measurements, or performing technical tasks, attending to special cases or exceptions defined in the text.


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 9-10 texts and topics.


Compare and contrast findings presented in a text to those from other sources (including their own experiments), noting when the findings support or contradict previous explanations or accounts.


  • A screen to show the video and text copies of the lesson Physical Weathering: Definition, Types & Examples, 1 per student
  • Copies of the lesson quiz, 1 per student
  • Images showing examples in nature of each type of physical weathering
  • Lab books, 1 per student
  • Pens or pencils, 1 per student
  • Exfoliation model
    • Block of sculpting stone (such as alabaster, limestone or soapstone), 1
    • Hammer, 1
    • Chisel, 1
    • Safety glasses, 1
  • Salt crystallization model
    • Medium beaker, 1
    • Salt
    • Water
    • Plastic spoon, 1
  • Frost wedging model
    • Cardboard milk cartons, 2
    • Water
    • Plaster of Paris
    • Small balloon, 1
    • Scissors, 1
    • Plastic knife, 1
    • Plastic spoon, 1
    • Ruler, 1
  • Abrasion model
    • Small container with lid (such as a food storage container), 2 per group
    • Rock, 1 per group
    • Piece of chalk, 1 per group
    • Digital scale, 1 per group
    • Stopwatch, 1 per group
    • Sand
    • Gravel
  • Root wedging model
    • Paper cups, 3 per group
    • Plaster of Paris, 1 cup per group
    • Water, ½ cup per group
    • Plastic spoon, 1 per group
    • Plastic knife, 1 per group
    • Permanent marker, 1 per group
    • Ruler, 1 per group
    • Potting soil, 1 cup per group
    • Bean seeds, 1-2 per group
    • Spray bottles filled with water, 3-4 for the class



  • This lesson plan consists of three demonstrations, conducted by either yourself or volunteers, and two activities that the students will complete in groups of 4.
  • Prepare the demonstrations as follows:
    • Exfoliation
      • Purchase a block of sculpting stone, or create a block using a cardboard milk carton and plaster of Paris.
      • Lay out a hammer, chisel and safety glasses.
    • Salt crystallization
      • Fill a medium beaker half full with water.
      • Set out a plastic spoon and salt.
    • Frost wedging
      • Cut the tops off of the cardboard milk cartons.
      • Set the cartons alongside the plaster of Paris, water, plastic knife and spoon, balloon and ruler.
  • Prepare lab stations for groups of 4 with the following activities:
    • Abrasion model
      • Add some sand and gravel to the two containers. Place the lid on each.
      • Place a rock on top of one container and a piece of chalk on top of the other.
      • Provide each station with a digital scale and stopwatch.
    • Root wedging model
      • Soak the bean seeds in water over night and provide each group with 1 or 2.
      • Add approximately 1 cup of potting soil to the first paper cup.
      • Add ½ cup of water to the second paper cup.
      • Add 1 cup of Plaster of Paris to the third paper cup.
      • Provide each station with a permanent marker, plastic fork and knife.


  • Begin the lesson with the demonstrations.
  • Put on your safety glasses and bring students' attention to the sculpting block. Show students how using the hammer and chisel causes pieces of the rock to fall off. As you do so, have students describe what you are doing to cause the rock to break. Ask for volunteers to try.
  • Show students the beaker of water. Ask them to predict what will happen when you add salt and stir. Do so and ask students to predict what will happen if you leave the beaker in the sun.
  • Finally, ask for some volunteers to help with the last demonstration.
    • Add plaster of Paris and water to the bottom of both milk cartons (enough to create a block roughly 3 inches cubed).
    • Have students mix the plaster of Paris with the spoon until it is the proper consistency.
    • Fill the balloon with water until it is approximately the size of a golf ball. Tie off the end of the balloon.
    • Ask a student to push the balloon 1-2 inches into the top of the plaster of Paris and hold it there until the plaster begins to set (about 3-5 minutes).
    • Have another student use the plastic knife to score a groove a couple of inches deep in the second block of plaster. The groove should not extend to the ends of the block.
    • Once the plaster has dried, remove the blocks from the milk cartons. Ask a student to measure the length and width of the groove in the second block and to write the data on the board. Pour some water into the groove.
    • Asks students to predict what will happen to the blocks when they are placed in the freezer overnight.
    • Allow the plaster of Paris to dry for the rest of the period and then place the blocks in the freezer.
  • Explain to the class that they have been observing demonstrations of physical weathering and that they will be learning more about physical weathering in today's lesson.


  • Distribute copies of the lesson Physical Weathering: Definition, Types & Examples and pens or pencils.
  • Watch the video, pausing at each section.
  • After each section, ask students to turn over their papers and work with a partner. Without looking at the text copy of the lesson, have one partner summarize the main term in the section and the other summarize an example from the section. They should then write both summaries in the margin. (You may want to demonstrate what this would look like after reading the first section.)
  • Once students have written their summaries, ask for volunteers to share what they discussed with their partner.
  • Finally, check for understanding by having students complete the lesson quiz.

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