a hand lens a stopwatch a thermometer a centimeter ruler
I gave my students this multiple choice question: A student measured how quickly a car rolled down a hill. Which tool should the student have used to measure how quickly the car rolled down the hill?

Only one answer is correct among these 4 choices:
- a hand lens
- a stopwatch
- a thermometer
- a centimeter ruler

Could you tell me which one is correct?

a stopwatch