Class can be a big bore, especially when you are in way over your head!

Tip of the day today:
Read the first chapter of your text before class.
This will allow you to at least be familiar with the terms and content - even if you don't understand it, yet.

It is too much to ask to understand material the first time you hear it. 
Don't expect to understand everything just from class.  Do yourself a favor - read and be prepared.  If you read before class you will drastically reduce the amount of study time afterward and at test time.