塾 is one of the most commonly used Japanese kanji, and it also has a lot of special readings in addition to the standard onyomi and kunyomi readings.
ONYOMI 音読み
KUNYOMI 訓読み
ジュク juku
Examples
あの子を無理に塾に通わせるのは反対だね。I’m against us forcing the child to go to cram school.彼は週に三回塾に行く。He goes to a tutorial school three days a week.彼は塾で勉強している。He studies at a cram school.私の塾はここから遠い。My cram school is a long way from here.