Heaven Help Us (1985) on Netflix

In this coming-of-age comedy set in 1965, Michael Dunn is a recently orphaned Boston teenager who is sent with his younger sister to live with their grandparents in Brooklyn. Once there, he befriends his misfit Catholic school classmates and a reluctant young monk, rebelling and discovering who they are, and often with hilarious results. Michael also falls for Dani, the local hangout owner's tough-as-nails daughter. But the repressive monks of St. Basil's will stop at nothing to prove that their ways are the right ways and their word is law...even if it means destroying their relationship.