I can do this for you.

But i know you said php and mySQL, I can only do asp.net (vb.net) and MSSQL.

Features will include:
-Whatever you said up top.
- "a white board" setting -> a chat room with a live white board, the teacher is using. I am not too sure about this control. I will not be creating it from scratch, and will be looking for an already available one. if there is one, i can garuntee its not going to be free.

$750 with fully coded design, 4 months hosting, database, programming of site.

thanks