Theresa

The Girl with Blue Vest played a minor role in "T.M.I.", where she asked Randy Marsh: "What's a penis?". A black haired version of her appeared in "The List" and "Elementary School Musical". She is currently the only known student to wear a vest.

Appearance
While she was initially shown with black hair, as of "T.M.I.", her hair is brown. She wears a light orange, long-sleeve shirt, a blue vest, and a dark green skirt. She also has green hair ties, which she uses to put her hair into two, puffy pigtails.

Personality
She seems to be one of the more innocent fourth graders. An example of this is her lack of sexual knowledge, as shown in "T.M.I.". This is in contrast to most of the fourth grade girls, many of which have been shown talking about some sort of sexual relation.

Prominence

 * "The List" - She was shown as a member of the List-making committee.
 * "Elementary School Musical - She was shown singing and dancing.
 * "T.M.I." - Her first speaking role; she was shown in the classroom for the first time. She asked Randy Marsh, "What's a penis?" while he is explaining his flawed version of the T.M.I. formula.