Do (one's) homework phrase
To spend time studying about a subject or a topic carefully, particularly before a meeting, a speech that you have to express your opinions on that subject, or topic.
Though he did his homework before the interview, he could barely answer the interviewer's questions.
From the way he confidently answered all the questions on that topic, I'm sure that he'd done the homework.
To memorize something so well that you can say or do it without having to try or think
To prepare for something
Used to describe starting to understand or learn about something.
To be mentally and emotionally prepared to endure someone or something
To learn a job by watching and copying how an experienced worker does it
The verb "do" must be conjugated according to its tense.
The origin of this phrase is not clear.
It was often said by a photographer when he would like small children to look at the camera and smile before he took a photo.
When the photographer said “watch the birdie”, all of us looked at the camera and smiled.