For the teacher demonstration:

• One Styrofoam or plastic cup
• Stopwatch
• Yard or Meter Stick
• Water
• 5-gallon bucket
• Drop cloth or tarp (or conduct demo outside)

Each group needs a variety of object pairs, such as:

• Balls of different sizes and weights
• A book and a sheet of cardboard of the same length and width as the book
• Objects that encounter more air resistance when dropped than the other objects (i.e., a feather or a sheet of paper)
• Other options for objects to drop: coins, plastic bag, play plastic army men, or other objects that are exactly the same.