Что это?

A place for students to put questions for the teacher (or other students) to answer at a later time.

Где его найти?

Posted on the wall.

Как мне его использовать?

If there isn’t time to answer a question, or if the question isn’t relevant to the activity at hand, try writing it on a Post-it or dry-erase “parking lot” so you can get back to it later. But make sure you do get back to it eventually!