How common is depression in children?

Please help me write a case study on childhood depression that I am struggling with. Here are the instructions.

Imagine yourself to be a counselor at a community mental health agency. You have been asked to share your thoughts in a meeting of a parent-teacher association at the local elementary school on the subject of childhood depression.

Write a 4- to 5-page report in a Microsoft Word document summarizing your thoughts that you will share in the meeting. In your report, include the answers to the following questions:

How common is depression in children?
How is depression in children different from depression in adults?
How are children assessed for depression?
What signs should parents and teachers notice that suggest that a child might need to be evaluated for depression?