What you may do on a chess board — what a pupil may have to study (3,5)
I believe the answer is:
set piece
But I can't explain it at all! Could you help me understand?
(Other definitions for set piece that I've seen before include "corner, say" , "Formal and carefully structured speech" , "Piece of writing arranged for maximum effect" , "Standard manoeuvre" , "Rehearsed move" .)