校 school

木 (tree) + 交 (combine) Same-ON

★★★★☆

10 strokes

Onyomi

KOU	All the jocks at my school were total COLONS.

Mnemonic

Our schoolhouse is built out of trees combined together.

Jukugo

高校(こうこう)	high school ★★★★★ 高 (tall) + 校 (school) = 高校 (high school)
学校(がっこう)	school ★★★★★ 学 (knowledge) + 校 (school) = 学校 (school)
専門学校(せんもんがっこう)	trade school ★★★★☆ 専門 (a specialty) + 学校 (school) = 専門学校 (trade school) a trade school, like for electricians or anime voice-over actors.
中学校(ちゅうがっこう)	middle school ★★★☆☆ 中 (middle) + 学校 (school) = 中学校 (middle school)
高校生(こうこうせい)	high school student ★★★☆☆ 高校 (high school) + 生 (life / birth) = 高校生 (high school student)
小学校(しょうがっこう)	elementary school ★★★☆☆ 小 (small size) + 学校 (school) = 小学校 (elementary school)

Lookalikes

	Meaning	Hint	Radical
校	school	WOOD	木
郊	suburb	TOWN

The school is made from WOOD, but

the suburb is a big TOWN.