Do you know of a cheap internet service?

I am in the US. I need it mostly for school. I thought I could survive without home intenet by using public wifi (coffee shops, library etc) but it got really annoying really fast when you have to leave the house just to [b]submitt[/b] an assignment or do a 5 minute timed quiz.

I've been using my phone to google this but don't see much. I don't want a contract.