Raven today has a lesson on the principle of Archimedes. She knows it is very difficult to understand by simply explaining the principle and deciding to do an experiment.
She needs a liquid or a fluid so she uses a glass, she lowers herself on the floor, she has high heels, stokings and very tight skirt, she takes off her thong and pisses it in with her hairy pussy. All students have to do it. Now the teacher dips the Chinese balls into the piss and demonstrates the principle of Archimedes. As a task all students will have to repeat the experiment.