"Middle- and high-school teams will demonstrate unique devices they have built to compete in the "Ball Fling Contest," the annual Invention Challenge hosted by NASA's Jet Propulsion Laboratory, Pasadena, California, on Friday, Dec. 4. The objective is to create a device that can propel three supplied playground balls to three different targets in less than 60 seconds. Point values are awarded for each successfully completed target. The winner will be the team whose device accumulates the most points. Twenty-one student teams from schools throughout Southern California will compete. The student teams were invited to the JPL Invention Challenge based on results from two regional contests held in November. Three teams of JPL engineers and scientists will also compete. While the contest rules change each year, the goal is the same: to give students an opportunity to be creative and have fun with math, science and engineering."