The toy must calculate the person's speed/velocity
Explanation:
Since the school toy given to Henry can be used to tell how fast someone is moving, the toy must be able to calculate the person's speed/velocity using the <u>average distance</u> covered by the person divided by <u>time taken</u> to cover the distance; average distance ÷ time taken.
The toy must be able to determine the parameters (average distance and time taken) in order to be able to calculate the person's speed/velocity