I can't think clearly. how can i tell if my depression interfering with my class work?

Can Have An Affect: Depression can definitely impact you academic performance. You will want to be sure to see out proper treatment. Until proven otherwise, the presence of depression would be a likely cause of poor concentration, decreased motivation, and trouble completing tasks.

Sounds like it is!: Not being able to think clearly is one of the symptoms of depression. Not thinking clearly would certainly interfer with any class work.