| 5 skinny rubber bands | 1 board | 15 weights |
| 2 paper clips | 1 clamp | 1 bucket |
| 2 index cards | 1 ruler | 2 pieces of cellophane tape |
2. Hang the skinny rubber band from the hook. Use the second hook (paper clip) to hang the bucket from the rubber band. See Figure 1.
3. Add weights gently until the bottom of the rubber band is even with the bottom of the index cards (see Figure 2). Write down how many weights you use in the chart below.
4. Repeat the experiment using 2 skinny rubber bands side-by-side. Then repeat for 4 and 5 rubber bands. Remember to record your answer each time.
5. We are going to use a graph to help us predict the number of weights needed to stretch three rubber bands. Plot the data you have already recorded and use a ruler to draw one straight line through your data points. You may not be able to get the line to go through all of them, just come as close as you can.
| NUMBER OF SKINNY RUBBER BANDS | PREDICTION | WEIGHTS NEEDED |
|---|---|---|
| 1 |  |
|
| 2 | |
|
| 3 (do last!) | |
|
| 4 | |
|
| 5 | |
|
6. Look at your graph and predict how many weights will be needed to stretch 3 rubber bands. Record your prediction in the chart.
7. Now do the experiment to find out how many weights are needed. Record your answer. How does it compare to your prediction?
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