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Main Curriculum Tie:
Background For Teachers:
Student Prior Knowledge:
Intended Learning Outcomes:
Step 2. Have students group around the doorway and review the definition of gravity. ("Gravity pulls objects toward the earth; gravity is a force.") Drop a few pennies to show the power of gravity as they end up on the floor. Then ask the class:
Step 3. Ask the students: Why don't the coins get pulled all the way to the ground? Is the "stretch" of the Slinky helping to overcome or slow the force of gravity? Which of our predictions was correct? What observations could we record about what has happened?
Step 4. Ask students what might happen if you increase the amount of pennies (or the weight in the cup). Record predictions and repeat the experiment with ten pennies. Mark where the Slinky stretches to when the cup stops. Why did the Slinky stretch more with the additional weight? What forces were involved? Continue to add coins as time permits and mark the amount of stretch the Slinky uses to counteract the force of gravity.
Step 5. During the next time period together, student groups will be creating their own device, a spring scale, for measuring the stretch of a rubber band and its effect on the force of gravity. Have students stack books into two identical piles approximately 8 inches high and 9-10 inches apart on a desk. They will place their rubber band around a ruler and then place the ruler on the two piles of books so the rubber band is suspended in the middle from the ruler (like something hanging from a bridge).
Step 6. Bend the paper clip into a hook and attach to the rubber band. Using the washers for weight, students will be measuring the amount of "stretch" or force used by the rubber band to overcome the pull of gravity.
Step 7. Fold a paper in half. Across the top, label the two columns: "Our predictions" "Actual amount of stretch." Groups will predict the length of their rubber band as they place different amounts of washers on the paper clip hook. They will then measure the actual distance from the hanging ruler to the washers and record the two on their paper. There will be two colums of data, one that is predictions and the other the actual measurements.
Step 8. As students work together, encourage them to discuss their observations about gravity and the force used to overcome it.
Step 9. Discuss experiments and results as a group. Have the class create two conclusions in sentence form that will explain the results of their findings. ("A force is required to overcome gravity." "Heavier objects require more force than lighter ones to overcome gravity." "The rubber band stretched more (worked harder) to keep gravity from pulling the washer to earth with heavy stuff.") Help students use key words in their explanations to show understanding.
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