The back of her skirt was flipped up and stuck to her shirt

(chapter originally by SpiralFelix at writing.com)

Isabel walked down the hall, oblivious to the view she was giving to anyone behind her. The black tights she had intended for modesty instead gave the public a detailed view of the girl's shapely ass as she strode forward. The outline of her panties was clearly visible, even if their color or design couldn't be seen from under the dark tights.

A member of the janitorial staff must have removed the 'Wet Paint' sign a bit prematurely, as some of it clung to the back of Isabel's shirt when she leaned on the bathroom wall. And when she had flipped her skirt up, it didn't take much for the light piece of fabric to stick, preventing it from falling back down to cover her ass again.

No one walking behind her seemed inclined to alert the blonde bombshell to her current predicament, and an audible groan could be heard when she disappeared into a classroom. Isabel spotted her usual spot in a middle row was open and walked over and set her bag down. After a moment of getting her notebook out, she sat down on the chair, trapping her lifted skirt between the chair and her back. The moment of pause while she stood there put her ass on display for a dozen or so students seated in the rows behind her. She now had their attention.

The chairs in this particular classroom had holes at the base of the back, allowing some flexibility for the chair's back. This meant a few pairs of eyes were now focused on that hole in Isabel's chair. While not the spectacular view of her full ass from earlier, they were still able to see the very top of her tights and an inch or two of bare skin below the hem of her shirt. And, as Isabel leaned forward, resting her elbows on the desk, her purple panties peeked out from under the tights.

As class began, Isabel focused on taking notes about the lecture. As she hunched forward more and more, she pulled the hem of her shirt higher and the tights fell lower on her lower back. As her shirt rose, it took the back of her skirt higher along with it. The front of her skirt was still over her lap, so it placed more and more strain on the skirt's waistband.

This came to a breaking point when, halfway through the class, the clasp of her skirt broke. Isabel felt a slight snapping sensation and looked down, but didn't notice anything wrong and shrugged it off.

So, at the end of class, when Isabel rose from her seat...