Complete accident

The following incident happened after her 18th birthday. It happened a couple months into the school year, and was due to some serious bad luck.

In mid October, Lizzie woke up to her mother shaking her, urging her to wake up.

Lizzie: What is it, Mom?

Mom: You're going to be late for school!

Lizzie opened her eyes and looked at the time. She had just twenty minutes to wash up, get ready and get to school! She jumped out of bed and headed straight for the bathroom, eager to shower and take care of her business. After a quick shower, she brushed her teeth, dried off, and went to get dressed. She pulled on the first pair of panties she could and looked at the time. Only ten minutes! She didn't have time for pants, so she pulled on a dress and ran downstairs. Her mom was waiting by the door, and Liz quickly put on her shoes, got her backpack and followed her mom to the car. A quick drive later, Liz ran to the school, making it inside her classroom just before the tardy bell rang. 

Her first class was Calculus. She enjoyed math, so she picked up the equations and graphs with little problem. The next class was history, which she wasn't too happy about. Her teacher, Mr. Reynolds, was old, boring, and very strict. If he caught you dozing off or even looking anywhere other than the front of the room, he would make you stand in the front of the room facing the board so you couldn't look anywhere else. She got through that class just fine, along with the class after that, English.

Lunch was after that, and she was able to sit and chat with Jackie about their day, since they didn't share any classes, but had a couple of the same teachers. After lunch, Lizzie had Science, which she enjoyed because of the hands-on experiments. Today was no different, but halfway into the experiment...