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Have students read the entire lab and discuss the following:
- Review how glaciers move and erode surfaces.
- Discuss what the ice and sand represent.
- Discuss the limitations of the model used in this activity.
- Discuss how force and pressure are related. Remind students that the same force can produce different pressures, depending on the area over which it is applied.
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Materials and Preparation
- large piece of ice
- paper towel
- piece of wire
- square of hard plastic
- handful of sand
- data table
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- Place the paper towel on your desk. Put the piece of ice on the paper towel. Try to quickly force the wire into the ice. Record your observations.
- Slowly but firmly push the end of the wire against the ice. Hold it there for several minutes. Record your observations.
- Place the plastic square on your desk. Rub the piece of ice back and forth on the plastic square. Observe the surface of the plastic. Record your observations.
- Place the sand in a layer on the plastic square. Try to quickly pick up the sand with the ice. Record your observations.
- Slowly but firmly push the ice down onto the sand. Leave the ice on the sand for several minutes. Remove the ice from the sand, and record your observations.
- Clean the plastic square of sand. rub the sandy side of the ice back and forth on the plastic square. Observe the surface of the plastic. Record your observations.
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- Which method worked the best for pushing the wire into the ice? (slow, firm push) How did inserting the wire demonstrate how glaciers melt? (this models the high, constant pressure exerted by accumulating layers of snow and ice in a glacier).
- Which method worked best for picking up the sand? (picking up the sand slowly).
- How could you remove a wire stuck in ice without destroying the ice block? (by pulling slowly and steadily, or by slowly pushing the wire completely through the ice).
- What was happening at the site where the wire or sand was slowly pushed into the ice? (the high pressure was melting the ice at the point of contact).
- What happened when you release the slow, steady pressure? (the melted ice refreezes, picking up the sand).
- Which caused the greatest change on the surface of the plastic, the smooth ice or the ice embedded with sand? How did this model demonstrate the effect of glaciers upon bedrock? (the ice with sand embedded scratches the plastic in the same way rocks carried in glaciers scrape the ground).
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Assessment and Extension Idea
Ask students to write a short paragraph explaining how the glacier model is similar to actual glaciers.
For an extension activity, have students design a model that shows glacial deposition. They should test the model. They should then decide how it is similar to actual glacial deposition and how it is different.