入 put/go in

Unlike the lookalike 'person' kanji (人）, the top of 入　bends left, so you can say,
'I take my NEW axe and put it in your left side, you bourgeois pig!!!! '

entrance ★★★★☆ NOKURI
入 (put/go in) + 口 (mouth) = 入り口 (entrance)

entrance (often shortened to 入口）

check in hospital ★★★☆☆
入 (put/go in) + 院 (institution) = 入院 (check in hospital)

check into the hospital - not for a simple exam, but like you have to stay there at least one night, you're too sick to leave.

to start school at a new school ★★☆☆☆
入 (put/go in) + 学 (knowledge) = 入学 (to start school at a new school)

admission fee ★☆☆☆☆ NP
入 (put/go in) + 館 (big hall) + 料 (ingredients / fees) = 入館料 (admission fee)