I brushed my teeth before school.

Meaning: This sentence describes an action where a person cleaned their teeth prior to attending school.

Choice of Words: Brushed is the past tense of the verb "brush," which means to clean something by rubbing it with a brush. Teeth is a noun that refers to the hard, white structures in the mouth used for biting and chewing. Before is a preposition that indicates a time or order. School is a noun that refers to an institution for educating children.