- Superball – 1 per group
- masking tape – 5 pieces per group, (or a whiteboard marker) to record bounce heights
- Tape measure (at least 10 feet) - one for each bouncing area

Time required: 25 - 35+ minutes
Description: The purpose of this lab is to investigate percents (and decimals), and be introduced to the exponential function. This lab also explores unit conversion in recording bounce elevations as accurately as possible.

- Each group of four will record the initial elevation of their superball, and the maximum elevation attained after one and two bounces.
- After each group has recorded their data, they will calculate the amount of recoil of their superball as a percent.
- In the competition, the instructor will put a mark on the whiteboard, measure the elevation of the mark, and ask students to determine the height at which they need to drop their ball so that it reaches the given elevation after one bounce. Groups should mark their team name on a piece of masking tape, and perform the drop from their calculated height, with the instructor marking the result and determining the winner.

Implementation notes (follow up/discussion questions, pedagogical recommendations, etc.):

- This lab is suggested to follow the introduction of exponents. A quick review of percents and unit conversion (for example, how to convert 5 ft, 2 ¼ inches to 5.1875 feet).
- After the lab:
- Discuss how the percent recoil of their superball might change on different surfaces, in a moving elevator, or if the ball were given some horizontal motion.
- Discuss the other factors that affect the recoil, like friction. Would the percent recoil be the same if they dropped the ball from a tall building?

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