Height of players Color of the baseballs thrown Order in which the players throw Spot from which players throw
I gave my students this multiple choice question: Three baseball players investigate to see who can throw a baseball the farthest. They mark off an area on the playground for their investigation. Which should they keep constant?

Only one answer is correct among these 4 choices:
- Height of players
- Color of the baseballs thrown
- Order in which the players throw
- Spot from which players throw

Could you tell me which one is correct?

Spot from which players throw