Each group needs:

• 1 empty, clean two-liter plastic soda bottle (ask students to bring from home or collect from recycling center)
• 1 pair of scissors
• tape
• 6-8 large index cards (4 x 6-inch size works)
• waterproofing materials to wrap over the index cards (aluminum foil, plastic wrap, etc.) so that the index cards do not disintegrate in the water
• pen or marker
• wooden dowel, ~¾-inch (2 cm) diameter (to fit into the bottle opening with a little room to turn) and longer than the length of the soda bottle; dowel can be re-used (Alternative: If large-enough dowels are not available, use smaller dowels and drill holes into the bottle cap big enough to accept the dowel and allow it to spin.)
• timer, clock or watch (to count seconds elapsed)
• string

For the entire class to share:

• water source
• pouring container to hold ~ 2 liters water
• sink or outside area that can get wet