Harry Potter: Disappearing Powder
Harry, now feeling confident with the knowledge of the textbook, walked into the classroom with his back straight, unlike the rest of the students, who entered with slouched backs. They looked at Harry with envious eyes, as if they knew he was the new class favorite or something. They took their seats as the bell rung.
"Hello, class," said Mr. Johnson from his spot in the front of the classroom. "Today we'll be discussing solubility. That is a substance's ability to dissolve in something else. Now, today we'll also be doing something a little different. We'll be doing a little role-play. Now, I'll need a few volunteers, um…Potter, Weasley, Granger, Finnigan and uh, Longbottom, up to the front please." The five of them went to the front of the classroom, not really understanding what was going to happen.
"Okay, so Harry is an element. He's a pure substance that cannot be broken down. If Ron and Hermione hold hands –" Here he put their hands together, and they blushed "– then they are a mixture. Then can easily be separated by physical means." He yanked their hands apart. "Now, if we use a sticking charm on Seamus and Neville, they are a compound. Mrs. Granger, will you do the honors?" Hermione flicked her wand at Seamus and Neville, making them stick together at the shoulders, much to the laughter of everyone else. They struggled to get free, but they failed. "See? Now they are a compound. They can only be separated by chemical means. You five can sit now."
"But…we're still stuck," Neville pointed out.
"Oh, we can deal with that later. Sit," Mr. Johnson said.
"I can't sit when I'm stuck to Neville!" Seamus shouted.
"Live with it, Finnigan! Sit!" They lumbered over to a chair, and they had great trouble sitting down. But Mr. Johnson moved on. "Now. A solute is the substance that is dissolved. A solvent is the substance in which the solute is dissolved. Can someone give me an example of a solute and solvent?"
"A potion brew for the solvent?" Dean guessed.
"And some boomslang skin and lacewing flies for the solute?" Neville said.
"Those aren't very soluble," Harry muttered to himself.
"Yes, good job, although I don't know what boomwang hair and lacing cries are," Mr. Johnson said. "Now we're going to explain the difference between colloids and suspensions. Two more volunteers…Brown, Finnigan. Up here."
"I'm still attached to Neville," Seamus interjected.
"Just get up here."
So Seamus-and-Neville clumsily clamored up to the front, looking oaf-like next to the petite Lavender.
"Alright, so Lavender is a suspension and Seamus is a colloid. A suspension has particles that scatter light and are too large to disperse without mixing. Eventually the particles settle back out. A snow globe is a perfect example."
"Ooh, snow!" Lavender exclaimed, making snowflakes fall around her with her wand. Her face lit up and she spun around. Mr. Johnson looked on in confusion.
"Er, right. Moving on to colloids. The particles are dispersed throughout and scatter light but are not heavy enough to settle out. Gelatin is a perfect example."
"Great, we're a big load of gelatin," Seamus muttered. Ron snickered.
"Thank you. You may sit down." They did so. "Now, someone go into the kitchens and bring me some chicken noodle soup and tomato soup." The students were confused at his request, but Michael Corner went anyway, and came back soon after with the requested soups.
"Ah, yes. See here, we have heterogeneous and homogeneous mixtures. The chicken noodle soup is heterogeneous –" he held up a spoonful of the soup "– because the mixture is different throughout. You can have broth, chicken, or noodles. And the tomato soup is homogeneous –" he then held up a spoonful of the tomato soup "– because it's the same throughout. See how it's smooth? It's all tomato soup. One substance. Well mixed." He put down the spoon and threw both bowls of soup in the rubbish bin.
"I'll never look at soup the same way again," Ron muttered.
"We're almost done here. We're at saturated, unsaturated, and supersaturated. I need more volunteers, erm…Potter, Longbottom, Patil. The Ravenclaw one," he added, before either of the Patils could ask which one. The three (sorry, four) students went to the front of the classroom.
"See, Harry here is like an unsaturated substance, because he has less solute than he can hold, below the saturation point. That's why he's so skinny." Harry looked down at his shoes. He didn't like where this was going. "Padma is like a saturated substance because she's right at the saturation point; she can't hold anymore. Her complexion is just right." Padma didn't seem bothered by this. "Neville, however, is like a supersaturated substance. He's beyond his saturation point, and it's overflowing; that's why he's chubby."
Hermione gasped at that. "Sir! That's unfair! You could get removed from your position for that kind of talk!"
Unfortunately, Hermione didn't get that much further, because the bell rung. Neville and Seamus clamored out first, Neville looking to be on the verge of tears.