1. Set a smooth piece of wood or sturdy piece of cardboard on the edge of a pile of books or small table to create a ramp.
2. Measure the carpet, bubble wrap, and sandpaper so they fit on the ramp and are all the same size.
3. Send your car down the ramp using the different surfaces and measure how far your car has travelled.
Which surface do you think will provide the most/least friction?
Can you explain why?