1) A hockey puck slides along an icy surface. What makes it slow down?

• It runs out of push
• It rubs against the ice
• It runs out of electricity

2) The rougher the surface, ... 

• the greater the friction
• the less the friction
• the same level of friction 

3) Which of the following is an example of trying to increase friction? 

• Squirting oil into door hinges
• Spreading grit onto icy roads (Will students know what "grit" is?)
• Waxing the underneath of skis

4) Which of the following statements is not true?

• Friction can only slow things down
• Friction is never useful
• Friction can stop things from moving