～てくれる・あげる・もらう

RuleVerb te-form + ageru/kureru/morau: shows who does the action for whom (the direction of the favor).

Curiosity

"A friend helped me" and "I helped (someone)" point in opposite directions. How does Japanese mark this direction of a favor?

Intuition

The giving/receiving verbs act as arrows. ageru points outward from me (or us), kureru points inward to me, morau is me receiving the favor. Attached to the te-form, they mean "do the action for / receive it done."

Visualization

oshieru (teach) → oshiete (te-form) → oshiete kureru (teach me, inward). Swap ageru/morau to change the direction.

教えるdictionary (teach)

Essence

te-ageru (I do for someone; can be rude toward superiors), te-kureru (someone does for me), te-morau (I have it done for me; the giver takes ni). Honorific forms: te-kudasaru, te-itadaku, te-sashiageru. Track the direction together with the subject and particles (ga, ni).

Examples

友達が宿題を手伝ってくれました。

A friend helped me with my homework.

私は弟に本を読んであげた。

I read a book for my younger brother.

先生に文法を教えてもらいました。

I had the teacher teach me grammar.

Mini-quiz

Which fits "a friend sent me a photo (for my benefit)"?