Bullying of a pupil

[Lolabun1]

Hi, over the last 2 lessons a pupil has been the target of pencil/rubber throwing. I have reported it but how can I catch the culprits (there are a few that it might be) if it happens behind my back without the use of a camera? Without proof I can't sanction them and I have reset the seating plan to disperse the pupils I think it was from but is still continuing.
Any suggestions would be appreciated.

I would suggest asking this in Staffroom (or 'reporting' your post and asking MNHQ to move it)

Ime there’s only really 2 things you can do. Either stand somewhere in class where you can see the reflections of the culprits in the windows or doors then spring them at the end of the lesson (so they can’t make a scene about you not possibly being able to see them) OR do the reprehensible but effective old trick of threatening a whole class detention. Someone will dob in the culprit before it gets to that