Why do this problem?

This problem lends itself to a systematic approach to trial and improvement. It could be used to extend learners when mass is being taught or revised. Alternatively, it could be used as an exercise in number work. A discussion of the role of the fraction in the problem might be interesting

Key questions

What is the most a lemon can weigh?

Do you have to have a multiple of $3$ lemons?

Is there more than one possible answer?

How you know you have all the solutions?

Possible extension

Learners could make a table to show the possible solutions and those which are not possible.

Possible support

Suggest listing some possibilities.