Board Thread:General Discussion/@comment-1650307-20171217055435/@comment-32173189-20180204214724

CartoonLover99 wrote: Hey did anyone else notice that the new girl had black hair and tan skin (anybody else think...)

That's why CPC and others were guessing Stella might be the new girl (even if we didn't see her face), even before the episode aired. It would have been kind of waste for the new girl to be a one-off character for a lesson of the day and then Stella being introduced.