Easy. There is TWO signals.
#1. She everytime disturb you, tease you for no reason. Ask for
your phone number and call you everyday. Ask for your email and
email you everday(except during exams periods, unless they very
free). If you see her everytimes, she is sure to be interested in
you!
#2. She always avoid you whenever you come near. She 
when you talk to her....just like very shy shy like
that.
