Jenny seems to have perked up while talking, and Emma's hoping having a new person to chat with will distract her, but she's hardly going to say that out loud, in front of Jenny.
(Why no, Emma's shyness around New Person is not at all a factor. Nope.)
"Cool. Um, I got the time right, right? Professor Slughorn should be here soon? Now? Ish?"
And with that, Professor Slughorn appears with a sunny smile on his walrusy face. They will be making a simple potion today, which does nothing but smell very different from any of its ingredients, as an introduction to some basic potions principles. He makes no issue about inter-House pairing.
Emma quietly begins assembling ingredients per instructions. They're not the most thorough instructions she's ever seen, but it's not exactly a complicated recipe.
Jenny makes a couple piles, but starts to panic rather quickly. She looks at Karen with a meek, for her, expression. "Er, am I doing this right?"
"It's my first day too! Let's just - go slow," says Karen, and she starts narrating what she's doing, reading aloud the labels on things and the instructions on the board and assembling more piles and starting to chop up the lily petals.
Miranda, meanwhile, helps Emma some, but seems more interested in reading their textbook about the theories they're illustrating than actually making the potion. It's not like it's going to do anything useful.
"Thanks," Jenny says weakly. She starts measuring out Standard Ingredient into a phial. "Sorry, I'm sorta new to magic. Like, all of it."
Emma's unbothered by this. Potions is just following directions. She is very good at that. As she grinds up some mistletoe, she peers over Miranda's shoulder. "Anything interesting?"
"Yeah, actually. There's an entire little appendix about potion smells and why they smell like things. Apparently most potions don't smell like their ingredients, which... is good, because some of them you have to drink and most potions ingredients aren't that tasty."
"Muggleborn?" asks Karen. "That's okay, you'll catch up. We know stuff from our parents, but we've none of us got to try things before."
"Yep, Muggle," Jenny agrees. 'Muggleborn' is new to her and she files it away. "It's... there's just a lot, you know? There's all this general stuff I don't know. Like Potions being wandless! If Potions is wandless, where's the magic come from?"
"Nothing about this specific potion. But apparently mistletoe is in a lot of potions that wind up smelling funny -" Miranda starts shredding something that needs shredding. "It also does other things, but this is one of them."
"You're not a Muggle," corrects Karen. "Just your parents, so you're Muggleborn. Or if you want to be very polite to yourself you can say you're a first-generation witch. And we're still magic, even if we aren't poking our wands at things. So we can make potions, but we couldn't teach Muggles how to do it, it wouldn't work."
As if on cue, something in the back of the room starts smoking. Emma successfully suppresses a giggle, but her eyes are laughing.
"Miranda says her mum is Muggleborn, so I bet she knows some things," says Karen. "That's probably why they went to Australia."
"I mean, it's suppose to smell nice if you do it right. I guess you could dunk sachets in it?" says Miranda dubiously.
"...I would say but who has those but I bet you if I look, my mum packed me some," Emma says, halfway between fondly and rolling her eyes. "We could check later."
"Er, do witches not normally go to Australia? Is 'avoid war zones' just a Muggle thing? ...please tell me if it is, that sounds unsafe."