Bonnie, and Bianca, and the other guests for the Pancake Race, went back to Kalos and Altomare and the other places they'd been before Hoopa signed them up for the race (with complimentary mandatory transportation). The Alolans stayed in Alola, though, and so did Ash, and two days later it was time for him to do another lesson.

"So today we're talking about water!" Ash said. "And ice, a bit, too, but mostly water. What do you know about water?"

"There's fresh and salt water," Lana said. "I hope I know enough about it because Popplio's a water-type and my family have several Water-type Pokémon!"

"Oh, you don't just mean the Type, right?" Kiawe checked. "Uh… I guess it rains?"

"We already did that one, didn't we?" Mallow said. "You get… salt water in the sea, and fresh water in rain, and they act differently I think? You can't drink the sea, but besides that. It's not safe for most plants either."

"Good," Ash told her. "Yeah, Grass types can usually cope with salt water okay in a battle, but it can be bad for them if they have to deal with it for a long time and they're not used to it. But there's a few other things to know about water before we really get started. Anyone else?"

Sophocles raised a hesitant hand.

"It's used for cooling things down, right?" he asked. "That sounds really silly now I say it."

"It's a good answer!" Ash replied. "You see, water takes a lot of heat to warm it up. A really massive amount, actually, it's harder to heat up water than a lump of iron or stone that weighs the same. That's one reason why it's good against the Fire type."

"Oh!" Lana said. "It conducts electricity! Especially salt water, which is why it's weak to Electric attacks!"

"Right," Ash agreed. "But there's special cases there."

"Ice floats," Lillie said. "That's unusual."

Ash nodded. "Well spotted! Yes, that is unusual, we're just used to it because there's so much water and ice in the world. But if you melt something else, then the solid sinks to the bottom of the liquid instead of floating on top."

Popplio came out of her Pokéball. "I've got one! I've got one!" she said. "Can I give an answer?"

Ash nodded, and Popplio formed a bubble before bouncing it on her nose.

"It's see through!" she said. "Nearly, anyway. And it's got currents in it, too."

"It is see through, isn't it?" Kiawe realized. "It's not like, uh, lava. Even if you could swim in lava."

"We might do volcanoes in another lesson," Ash replied. "Maybe if Lokoko can learn Entrainment..."

He thought for a moment, then held up a Dive Ball. "Let's start by having a look at water!"

Silver came out with a flash. "Hi, everyone!"

"This is Silver," Ash introduced the young Lugia. "He's going to show us some of how water works. Okay, Silver, Hydro Pump!"

"Shouldn't we-" Lana began, then stopped and watched in surprise as the Hydro Pump didn't blast the whole classroom. Instead, Silver took control of it with Extrasensory only a moment after the attack came out of his mouth, and it formed into a giant spherical water-globe.

"Ooh," Popplio gasped. "That's the kind of thing I really want to do! Only, as a bubble with air in it, not a giant water blob by itself."

"So, this is water!" Ash said. "And it makes a really good shield, if you can move it around, because it's heavy – a lot heavier than air, after all! - and you can see through it, plus if someone tries to get rid of the water by burning it away or freezing it it'll take a lot of energy to do it."

He sent out Buizel next, and the Water-type took a run-up before jumping into the bubble with a splash.

"Buizel's showing how you can swim around underwater," Ash added. "That sounds obvious, but it's good to think about it when you get a chance, since battling on water or in water you sometimes can't see what your Pokémon is doing. Underwater you can be attacked from a lot more different directions, but you can also dodge in more different directions, so it's a trade off… and, even though a lot of attacks have to push through the water and lose their power, you can use the water to hit someone and it's different. A move like Whirlpool can really cause a Pokémon trouble if it hits them underwater… but now let's see something else cool. Buizel, Aqua Ring!"

Buizel swam to the top of the bubble, sprang out, used Aqua Ring, and dropped right back in again.

"Suicune!" Ash added, and got Suicune (which was a bit of a novelty). "Suicune has a special power where she can make water pure. That changes how it works, but first, Pikachu, Thundershock!"

Pikachu directed a jet of electricity at Buizel, and the attack lit up the whole sphere. Buizel's Aqua Ring dropped out of him with a muffled brring sound, and he let it hover there for a few seconds before going to pick it up again.

"So that's an Electric attack against normal water," Ash said. "Now, if Suicune makes it so the water is super-pure, so it's just water and nothing else at all…"

Suicune tapped the water with her paw, and Pikachu used Thundershock again.

This time the pattern of lightning was different, fizzing around the outside instead of going into the middle.

"That's because water conducts electricity, not because it's water, but because of other things in the water!" Ash said. "Salt water conducts electricity more easily, and really pure water doesn't, but it has to be really pure."

Then the egg by Lillie's desk hatched into an Alolan Vulpix.

"Good afternoon, little one," Suicune said, with a nod. "It's nice to meet you."

Vulpix looked at her, then at the giant bubble of water.

"Are you going to stop the lesson?" she asked. "I was learning things. Are you going to do ice next?"

"We'll get started again in a bit!" Ash said. "But I think we all want to say hello to you first!"

"Hello," Lillie supplied. "You have good manners."

"You haven't seen me when I'm annoyed," Vulpix replied. "I haven't seen me when I'm annoyed. Maybe I do?"

Everyone said hello to Vulpix, and she said hello back, and after that Ash resumed by talking about surface tension.

"Water likes to cling together," he explained. "It's why when a window or floor gets wet, but not too wet,you see drops on it instead of a sort of flat layer, because the water pulls itself together. It's like there's a bit of a skin on it, and it's how Surskit skim across water… it's not very strong by itself, but Pokémon can make it stronger and so you can do some neat things with it. Like how my Greninja uses a lot of his water attacks!"

"Your Greninja?" Sophocles asked. "Oh, are you going to send him out?"

"I bet he's already in here," Togedemaru guessed, looking around. "They're ninja, so they can be really sneaky."

"Or maybe that's just what they want us to think," Bounsweet said.

"But maybe that's what he'd want us to think, and so he really is hiding," Mallow frowned. "I'm confused."

Greninja came in through the door.

"Grovyle said that as a ninja I should arrive late," he said. "And say that it's because a Litten crossed my path or I was helping someone with groceries. I don't really get it myself."

"Hi, Greninja!" Ash waved. "Great timing!"

"Oh, I must have got it wrong, then," Greninja decided. "If I'm not late or early, maybe I got ninja confused with wizard."

He used Water Shuriken, and left it spinning on his palm for everyone to see.

"So it's not just surface tension making the water attack shaped like that," Ash explained, to everyone. "Otherwise it'd just be sort of a blob. But surface tension's involved in making sure it has definite edges, and also in making it so it hits instead of just splashing."

"There's a lot more behind Pokémon moves than I thought," Kiawe admitted.

"Now, let's move on to ice!" Ash said. "Like Lillie said, ice floats, but ice is a weird substance by itself too. Let's have some, Buizel!"

Buizel used Ice Shard, resulting in a dozen little pieces of ice floating around inside Silver's water bubble. Then the Psychic-type extracted them, and Greninja put one each on everyone's desks to pick up.

"So the first obvious thing about ice is that it's cold," Ash said. "And even though Ice is weak to Fire, it actually takes a lot of heat to melt ice, so an Ice-type can use ice to shield itself from fire if it's careful about it."

Vulpix nodded.

"Should I take notes?" she asked.

"I'll do it," Lillie said.

"But that's not all there is about ice," Ash explained. "You can freeze other things into the water that ice is made of, like air bubbles, and if you make ice colder it also makes it harder to damage. That's because a lot of how ice moves about is because it's sort of… squishing around a bit, and the colder it is the harder it is to make those happen. Ice can also block electricity if it's cold enough that there's no water channels for the electricity to go down… oh, yeah! So, here's a question for everyone – what do you think would happen if Silver froze this ball of water?"

"It'd get colder?" Mallow suggested.

"If it's still moving, it would freeze in a weird way, right?" Lana guessed.

"Oh!" Kiawe said. "He'd drop it, because it'd be slippery now!"

Vulpix raised her paw.

"I think I have a guess?" she said. "Lillie said that ice got bigger when it froze, so if he froze it from the outside, it'd build up pressure as more of the ice froze. And then it'd explode."

"That's right!" Ash agreed. "Now, Silver, send that water ball outside and let's demonstrate!"

After the bits of ice shrapnel had finished falling, they sorted out what to do with Vulpix by going to visit Principal Oak.

He explained that he'd had it planned that one of the members of the class would get Vulpix as their Pokémon, and that he'd be keeping an eye on her to see how she was different from his own newly-hatched Fire-type Vulpix, but that it really was up to them who got her.

"It wouldn't make sense for me to decide," the Principal added. "I've already had my pix today!"

"Hmm," Kiawe said. "I say Lillie gets first pick!"

"I agree!" Lana agreed. "Lillie, it's up to you."

"And Vulpix," Ash reminded them.

"I think…" Lillie began, then clenched her fists.

"I want to be able to say yes," she said. "If Vulpix wants to be my Pokémon, then I want to be her trainer, but I don't know if I can be."

"Then let's give it a try," Vulpix said. "I can be patient. I think. I don't know that about myself yet."

She scratched her head. "Should I have a name? Greninja is Greninja, but Lokoko is Lokoko."

Everyone looked at Lillie, who went red.

"The only name I can think of is Snowy," she admitted.

"I'll take it!" the new Snowy declared. "Looks like you're stuck with me."

"Then let's get back to the lesson!" Ash said. "We can talk about how skating works, because it's something where nobody quite knows how it works but they've got a good guess…"

"Isn't it just that ice is slippery?" Silver said.

"That's right, ice is slippery," Ash agreed. "But the big question is why it's slippery!"

AN:

There's always more to learn, which is convenient.