Each group needs:

• 10-inch (25-cm) square, 1-inch (2.54-cm) thick piece of transparent Plexiglas to serve as a baseboard (available at hardware stores)
• 4 small wooden pieces or books to serve as corner supports for the Plexiglas baseboard
• 1 strong magnet (available at hardware stores)
• 2-3 steel ball bearings (various sizes, 1/18-inch and larger; available at hardware stores, auto parts stores, bicycle shops)
• 2 pieces of angle aluminum, a right-angle V cross-section 6-10-inches (15-25-cm) long (available at hardware stores)
• 1 large magnetic ball (this may be difficult to find at some hardware stores; magnetic tennis balls are available online at http://www.stevespanglerscience.com/product/1312)
• Trajectory Deflection Worksheet