Professor Sydney has four of her students with her, staying after class because they failed their exams. Of course, she has a plan to deal with this and give them a chance to make up the grade, but of course she had to shrink them first so they're super tiny. They cower under her since they have no idea what she has in store for them. Well she explains it to them. Since they failed the biology test, they're going to have to take a field trip into her stomach. Hopefully they will learn by experience.
She pops them in her mouth, telling them not to worry, they should survive the trip all the way through until she pulls them one by one out of her ass. She cleans them off and asks if they've learned anything. No? Well then they'll just have to go right back in until they do! She sends two more down into her stomach again and stuffs the other two in her ass.
She checks their notes to make sure they learned their lesson. She sees they took good notes but she thinks they could use a little extra credit, so she eats them again!