Mysterious Sandra

In Season 1 Episode 7 (Divide and Conquer), the new girl, Sandra arrives at Sheffield Institute and gains attention and popularity, especially with the boys. This makes the W.I.T.C.H girls jealous, mostly Will.

I just don’t get it – After Sandra’s challenge with Will to win Matt, she was never seen again, or heard of in the later episodes. Wasn’t she the popular girl at school?