Is my teacher being flirty or just quite fond of her....?

He asked her "Beach this weekend?" in front of the cl, asked her what she does there and when she is usually there, and said "I'll probably see you there one day." He commented her shoes once, teases her about her height, and smiles at her everyday. He doesn't act this way with any other student. Lately he has been finding an excuse to talk to her everyday. She's usually perky and always smiling. Once he woke her up and he kept on smiling. She's getting a good grade in his cl. She's 15-16 and he is around 34 and he's a student teacher.