Here's a link to circuit practice as provided by The Electronic Teaching Assistant, available on the web page of Professor J.A. Svoboda of Clarkson University, Potsdam, NY

This site has a lot of exercises to refresh your memory about current and voltage sources, Thevenin and Norton equivalents, dependent sources and a whole bunch more. It's set up with interactive graphs and a little pop-up calculator. It also tells you if you're right, and nobody's watching to see how much you fumble. There are a million examples, and its fun to see your skills improve as you go through them.

Of course, you're going to need to know how to do these things in ECE 304, because hand analysis depends on them. And you'll have to learn them on the fly if you're rusty, so don't be too proud to look things over.