The experiment in question asks the student to take several measurements for the period with different pendulum lengths.* Then it asks the student to pick a length, with justification, before proceeding to more complicated experiments.
The intended answer as given by the grading scheme is:
The student should pick the longest length. This is because the longest length has the lowest percentage error.
The answer that a student wrote is:
I pick the shortest length. This is because I only have 15 minutes left to do the rest of the experiment, so I cannot wait a long time between measurements.**
The student's answer is not wrong, in fact it is a very good reason, but it's completely different from the answer in the grading scheme. Is it appropriate to award points? If it is appropriate, is partial or full credit correct?
Related: Is it ethical to award points for hilariously bad answers? This answer is funny in its own way, but it's not hilariously bad.
Edit: since people repeatedly want to see the full question.
- Adjust the length of the pendulum, then measure the period.
- Estimate the percentage uncertainty in your value of the period.
- Repeat the above for at least two more lengths. Tabulate the results.
- Comment on the trend in your results.
- In the upcoming, choose ONE of the above lengths that you used.
- (i) Record your choice of length. (ii) Explain your choice of length.
- Vary [a parameter x which I have simplified out of the experiment]. Record the new period. Comment on the effect the parameter has on the period.
- Vary [a third parameter y which I have simplified out of the question]. Record the new period. Vary y again. Record the new period.
- It is suggested that the period is equal to k/y, where k is a constant. Use your values from (8) to determine k.
- Justify the number of significant figures in your value of k.
- State whether your results support the assertion that the period is equal to k/y.
- [And more stuff that I really don't see how they are relevant to the question].
*The length of a pendulum is related to its period by T = 2pi sqrt(L/g), where L is the length of the pendulum and T is the period. In other words, a longer pendulum takes longer to oscillate.
**The description of the experiment I gave is simplified. In the actual experiment, it takes up to one minute between measurements while using the longer length. With shorter length, it takes ~10 seconds.