Usually for that sentence you would say "Since we've finished our homework, you wanna chill at the mall?"
I think the "covered" you are thinking of would be used like this:
(At the end of a class, the teacher is announcing a test for next week)
"All right everyone, now that we have covered all of the material in this chapter, we are going to have a test over it, next week."
Covered is usually used when you go over or explain it. A teacher "covers" her class subjects because she explains them to the students. A textbook "covers" information because it explains it to the reader.
Edit: The "deal with" definition that you are seeing, doesn't mean the regular definition for "deal with" which is to take care of, or finish. This "deal with" means that it covers or relates to something basically.