This is the 8588th most frequent Korean word.
가르쳤다
"Taught" (past tense of "teach").
In this sentence, '가르쳤다' is used to indicate past action of teaching by '그는' (he).
그는 학생들을 가르쳤다.
He taught the students.
Here, '가르쳤다' denotes teaching a specific skill to '그에게' (him).
나는 그에게 새로운 기술을 가르쳤다.
I taught him a new skill.
In this sentence, '가르쳤다' means explaining and teaching the names of animals to '아이들에게' (to the children).