She starts messing with her clothes

She starts playing with on of the loose strings in her shorts. She pulls and pulls until they are transparent. She pays much more attention to not being seen rather than class. The teacher notices this and calls her up to tell the class what they are working on but before she says a word one of the classmates points out her almost nakedness. Mary-Kate looks down to her boobs and panties being seen as if her other clothes are invisible.