I consider Forms the unsung hero of Google Apps. Users tend to get stuck in the Google Docs world and may not even realize this program exists. Forms is a very useful program with many classroom applications.
If you want to explore Forms on your own, this video (9:05) will get you started, but I feel it leaves out some important information that can make Forms easier for you. My suggestion, poke around Forms for a short while (like 10 minutes), and then contact me before you roll-out your first classroom activity so we can fine tune things a bit. I’m sure you’re going to like this program.
Update: 7/2/15 An alternative video about getting started with forms.