Why do this problem?
This activity offers a starting point that can lead to a high variety of avenues to pursue.
Present the pupil with a kitchen roll (or similar) tube and introduce the activity as suggested. If the learner is not accustomed to exploring mathematically, you might consider encouraging them to look at all the angles involved (both of the required shape and the pieces cut off the $A4$). If s/he still needs more prompting then you might consider suggesting they explore these angles
There are further suggestions in the hints
Tell me what you have so far.
Which direction do you want to go in now?