How can I tell if this girl in my college cl is into me?

I am a College Student, and this semester I have a cl with this girl I think is really cute named Jade. We had a group activity in the cl the other day in which both of us ended up on the same team. Our team came in first, and during the activity she seemed to really enjoy my company. I talked to her more than anyone in the group and found out we have very similar interests. She also seemed to enjoy talking with me, as she was smiling almost the whole time she was talking with me, and laughed at my jokes. Even though some were admittedly bad. Still, I shrugged it off as two students trying to p time in cl and went home uming that was the extent of our social relationship until next class. Well yesterday, I got a facebook friend request from Jade and she is apparently single. I want to at the very least gauge her interest in me before asking her out on a date or anything of that nature, yet I don't really know how to do that exactly. She sits with an empty chair next to her in class, so I may switch seats. I don't know if that would weird her out though if I suddenly changed seats. What kind of things should I look for when I am talking with her to tell if she is into me that way. Also, what kind of things should I talk about that might help reveal how she feels about me, without making it obvious that I am into her? If there are other suggestions, please post them. All help is appreciated, thanks!