society > education > teaching > systematic or formal teaching > [verb (intransitive)] > teach in school (5)
to keep (also †hold) (†a) school: to run a school; also figurative. Now chiefly U.S.
to teach school: to teach in a school; to work as a schoolteacher. Now chiefly U.S. and Irish English.
intransitive. To work as a schoolmaster; to teach.