Does this indicate jealousy on the part of another girl towards me?

Ok so my teacher at college praises me in the cl and trying to build my self esteem through enforcing a positive self image as she knows I have problems with social anxiety disorder but after this, she is talking about presentations and how students are terrified of it. It is a small group at the college and one girl who has been a ***** to me in the past laughs at me because of that. She saw the teacher praise me but it was like two seconds later she wanted to bring me back down to feel bad? What do you think about a person like that? If I see another person praised even if I were jealous I am not so desperate to want to drag them back down but this girl was.Do you think that she was feeling the inevitable sting of envy at the positive attention of the teacher, combined with the fact another lecturer was actually attracted to me and she was being competitive? It just seems odd to behave like that. Why would she deliberately want to bring me down and make me feel put down?