To/For/At

To 

I was talking to my friend while I was doing my homework

I listened to music before I went to sleep

We all speak English in English class

I apologized to the teacher for being late for class

This book belongs to the school

Something bad happened yesterday when I got home

For

I was waiting for a friend to go outside

I asked permission from the teacher to find out if I could get out

He applied for a job

Better blame the one who didn't do his homework

He takes care of his dog every day

I've been waiting so long for the lesson to end

At

The photographer told us to smile

He stared at her and she said, don't stare at me

The sniper always takes aim before shooting

I was looking for my keys because I lost them

Dad said to point me to any car and he would buy it

They laughed at him because he answered the teacher's question incorrectly