If it's not central to the story, but there mostly to define the MC and maybe some of his or her relationships, it might be best to just show it as occasional flashbacks to critical points and ignore the rest of it.
I mean, if you really NEED to depict the character's time in school, the model to follow would be
Tom Brown's School Days By Thomas Hughes (published in 1847!). If important events happened there, but the actual schooling, is trivial, the Flashman Papers (a series of books by
George MacDonald Fraser chronicling the adventures of Tom's school bully, Harry Paget Flashman, and only references said school days in criticizing Brown's biased account of his behavior - he does not deny any of it, just says it was not as bad as Hughes depicted, while admitting that he was, and still is, a bit of a cad).