Tie identical weights to two strings of different lengths. Tie two different weights to a string. Tie identical weights to a long string. Tie two different weights to two identical strings.
I gave my students this multiple choice question: Choose the investigation that would best answer the question: Does the length of a string change how fast a pendulum swings?

Only one answer is correct among these 4 choices:
- Tie identical weights to two strings of different lengths.
- Tie two different weights to a string.
- Tie identical weights to a long string.
- Tie two different weights to two identical strings.

Could you tell me which one is correct?

Tie identical weights to two strings of different lengths.