Rockin Roots. Weathering causes rocks to break down. Acid rain, roots, freezing and thawing of water causes weathering in rocks.

Transcription

1 Rockin Roots Lesson Concept Weathering causes rocks to break down. Acid rain, roots, freezing and thawing of water causes weathering in rocks. Link In the previous lesson, students learned that rapid processes (volcanic eruptions, earthquakes, landslides, severe wind, tsunamis, etc.) quickly change landforms. In this lesson, students learn about the slower changes caused by weathering. In the next lesson, students will learn that moving water (waves, rivers, rain, etc.) and ice (glaciers) also cause erosion. Time 60 minutes Materials Whole class Computer LCD projector Powerpoint Presentation: Rockin Roots Freezer 2 Glass (Snapple-sized) bottles with lids, filled with water 2 Hand towels to wrap around the bottles 3-4 rubber bands to wrap around the towels Plastic wrap to wrap around the towels Per Group (groups of 2-3) Small plastic container with lid (e.g., salsa-sized, takeout condiment containers) Water (enough to fill the container above) Vinegar (enough to fill the container) Copper penny that is dirty or has been oxidized. Piece of chalk Small sealable plastic bag for the chalk Sand sample Plate/bowl for sand Individual Science notebook Hand lens 4.2 Rockin Roots PAGE 1

2 Advance preparation 1. Preview the Powerpoint Presentation: Rockin Roots. 2. Prepare two glass Snapple-sized bottles of water ahead of time by filling completely with water and capping. 3. Wrap the plastic wrap around one of the bottles. Wrap the towel around the bottle and secure it by wrapping the rubber bands around the Snapple bottle. 4. Place the wrapped bottle in the freezer overnight. 5. Be sure to remove the bottle from the freezer before the lesson, the following day. Teacher Note: The plastic wrap keeps the glass pieces intact. The towel will prevent contact with cracked or broken edges of glass, but use caution when disposing unwrapping the bottle. Procedure: Engage (5 minutes) Freezing water causes it to expand. Freezing water in rocks causes rocks to break apart. 1. Ask students if they have ever seen the effects of freezing a liquid in the freezer. Have students describe what they have observed. [Expected Student Response (ESR): Cans of soda explode. Plastic water bottles expand.] 2. Show the students the filled glass Snapple bottle. Have students make a hypothesis about what they think will happen when you place the bottle in the freezer overnight. Have students record their hypothesis in their science notebook: If I, I hypothesize because. [(ESR): If I freeze the bottle with water in it, I hypothesize the bottle will break because when the water freezes, it will expand.] 3. When students have recoded their hypothesis, unwrap the frozen bottle and have students record their observations in their science notebooks. 4. Distribute the Rockin Roots Notebook Page. Have students use this worksheet to summarize what causes the weathering of rocks by ice. Explore (10 minutes) Water causes weathering of rocks by gradually wearing down their surfaces. 5. Display a container of water and a piece of chalk. Explain to students that each group will have a piece of chalk (which represents a softer rock), and a container filled with water. Have students hypothesize what will happen when they shake the container. Have students record their hypotheses in their science notebook: I hypothesize because. [(ESR): I hypothesize the chalk will dissolve in the water because it will break in half.] 4.2 Rockin Roots PAGE 2

3 6. Distribute a container, lid, and piece of chalk to each group. 7. Have the students fill the container with water, place the chalk inside the container, and place the lid on the container. Have students shake the container for 2-4 minutes. 8. Have students record observations in their science notebooks. [(ESR): I observed the corners of the chalk were more round and smooth.] 9. Encourage students to make inferences about their observations. [(ESR): The shaking and water caused the chalk to break down.] 10. Refer to the Rockin Roots Notebook Page. Have students use this worksheet to summarize what causes the weathering of rocks by water. Explain (5 minutes) Water causes weathering of rocks by gradually wearing down their surfaces. 11. Display the Rockin Roots Powerpoint slide of the rocks weathered by water. 12. Have students compare how the breaking down of rocks in the presentation is similar to the changes that occurred with the chalk. [(ESR): The breaking down of rocks in the presentation is similar to the changes that occurred with the chalk because the outside edges of the rocks and the chalk both get smoother and rounder.] Explore (10 minutes) Acidic water causes weathering of rocks. 13. Have students hypothesize what will happen when they put a penny, which represents a harder rock, inside of a container filled with vinegar and shake it. Explain that vinegar represents acid rain, which is the result of air pollution. Have students record their hypotheses in their science notebook: I hypothesize because. [(ESR: I hypothesize the penny will not change because it is too hard, I hypothesize the penny will crack because the vinegar will wear it down.] Teacher Note: Acid rain is a rain or any other form of precipitation that is unusually acidic. Acid rain can have harmful effects on plants, aquatic animals, and infrastructure. Acid rain is caused by emissions of sulfur dioxide and nitrogen oxides, which react with the water molecules in the atmosphere to produce acid. 14. Distribute a container, lid, and penny to each group. Have students fill the container with vinegar, place the penny inside, and cap the container. Have students shake the container for 2-4 minutes. 15. Have students record observations in their science notebooks. [(ESR): I observed the penny looked brighter and cleaner.] 4.2 Rockin Roots PAGE 3

4 16. Encourage students to make inferences about their observations. [(ESR): The vinegar caused the penny to be shiny. 17. Refer students to the Rockin Roots Notebook Page. Have students use this worksheet to summarize what causes the weathering of rocks by acid. Teacher Note: The acetic acid in the vinegar dissolves the copper oxide on the penny, leaving behind a shiny, clean penny. Explain (5 minutes) Acidic water causes weathering of rocks. 18. Display the Rockin Roots Powerpoint slides of the weathering caused by acid rain. 19. Ask student to explain the similarity between the rocks in the presentation and the changes that occurred with the penny. [(ESR): The penny and the rocks are similar because both of them wore down or changed because of the acid in the water.] Explore (10 minutes) Roots of plants and burrowing animals cause weathering in rocks. 20. Distribute the pieces of chalk and the plastic bags, and have students place the chalk inside the bag and seal. 21. Have the students scrape the chalk with their fingernail through the bag. 22. Have students record their observations in their science notebook. 23. Explain to the students that this is a model of what happens when a root or an animal burrows or digs through a rock. Explain (5 minutes) Roots of plants and burrowing animals cause weathering in rocks. 24. Display the Rockin Roots Powerpoint slide of the rocks weathered by roots and the burrowing of animals. 25. Have students explain how this is similar to the changes that occurred to their piece of chalk. [(ESR): Scraping the chalk with my fingernail is similar to the rocks in the Powerpoint because animals also scraped the rocks down with their claws. The plants pushed through the rock just like my fingernail.] 26. Refer students to the Rockin Roots Notebook Page. Have students use this worksheet to summarize what causes the weathering of rocks by plants and animals. 4.2 Rockin Roots PAGE 4

5 Extend/Evaluate (10 minutes) Weathering causes rocks to break down. Acid rain, roots, burrowing animals and freezing water cause weathering in rocks. 27. Distribute sand samples and hand lenses. 28. Have students observe the shape and the edges of the sand grains through the hand lens. Direct students to write a description of the sand grains in their science notebooks. 29. Explain to the students that these sand grains are broken down pieces of rocks. Ask students to think pair-share about what caused the rocks to be weathered. 30. Have students use their notebooks to write four different ways that this sand may have formed over time. [(ESR): The sand was formed when rocks were weathered by frozen water, acid rain, roots of plants, and animals that burrowed into the rock.] 4.2 Rockin Roots PAGE 5

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