Claims & Evidence

Paraphrase and discuss:

You will make a model to help you determine how the steepness of a ramp would affect a skateboarder’s impact if he or she crashed. You will roll a ball down ramps of different heights and measure how far the cup at the bottom of the ramp gets pushed when the impact occurs. If the cup goes farther, there is a greater impact.

Do a demonstration of the basic set up of the experiment.

Distribute materials to groups:

• three books
• ruler for making a ramp (the kind with a groove in the middle is best)
• ruler for measuring book stacks and cup movement
• small ball
• Styrofoam cup with an opening cut into it for the rolling ball to enter

Students can complete the experiment in pairs or in small groups. If the students are in small groups, they can each be assigned lab roles.

• person in charge of placing the ball on the ramp
• person in charge of measuring distance moved by the cup
• person in charge of recording measurements

At the upper heights, the cup can slide up to 30 cm. If the desks are not large enough to accommodate this distance, the experiment can be carried out on the floor.

Lab Worksheet for Students:

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Review procedure:

1. Set up your ramp and cup as shown in the first picture in the data table below. Start by putting one book under the ruler.
2. Measure the height of the book or stack of books for each condition. Record this in your data table.
3. Hold the ball at the top of the ramp.
4. Let go of the ball and let it roll down the ramp to hit the cup.
5. Measure how far the cup moved because of the impact. Record this measurement in your data table.
6. Roll the ball down the ramp three times for each condition. Each of these rolls is a “trial.” Average the measurements you recorded for the three trials in each condition.

Students graph their data from their table.

Students can work together in their lab groups but each student should have a graph in his/her science notebook.

Interpreting data: Students should complete the graph and make an attempt at the claims statement before participating in Meeting of the Minds.

If students have additional time, they should begin to think about additional experiments that could be done.

For example:

What else might change the speed of the ball?

How could you test these factors?

Students should be prepared with graphs, claims statements, and their Meeting of the Minds sentence starters.

Give students some time to think about the following questions. (This activity can be done individually or in small groups.)

Ask:

• Are there other ways to test this claim?
• Should people who build skateboard parks worry about how steep the ramps are?
• Are there other things that might affect the speed of a skateboarder? Could you test them?

Students can record their thoughts in their notebooks. Remind students that these notes will be helpful when they write the following day.

It may be useful to have each group copy their graph onto large chart paper so that it is easier for the whole class to see and interpret.