Holly is at school early, and can see her classmates arriving. It's hard to make out details of these giant kids at her nearly speck size, but she can hear and thanks to her friend's fashion sense, she can tell it's Suzie approaching. Suzie is a pretty cool friend, with over the top style, and sure enough, she is wearing stilettos to high school: not the most practical choice. But if she is rocking the killer heels, that means pantyhose and a skirt, all of which will be easy for micro-Holly to climb. So Holly gets a running start and leaps..... flying through the air, since she weighs so little, her strength at this size impressive, but also her durability, landing with a splat against the straps of her friends heels. There is no chance anyone could hear that sound, even if it was loud to Holly's tiny ears, and as she climbs up, a quick look around and she shrinks further, down to a single mm, a true speck, and invisible on the material of Suzie's sheer nylon hose.
But those nylon hose are only sheer on the macro level: to Holly's reduced size the thin fibers evenly spaced make wonderful rungs of a ladder to climb the skyscraper that is her friend. Putting her airpods in, phone into her bag, Holly begins climbing her friend the stylish mountain, all while her first period lecture starts playing in her ears. The earbuds block out other sound, which is just as well, since being this small does cause some distortion to how human voices sound normally, but Suzie has most of the same classes as Holly, so she is technically in attendance but marked as absent:remote since no one knows she is there, not even the girl whose legs Holly is climbing all of first period into second.
Holly had to pause a few times, to type in comments or do work in her virtual classroom, though most of the teachers were chill about her not being on cam. But, she needs to figure out something for fourth period, since Williams is a prick about things and demands her being on camera for the first part of class. By the time third period rolls around, Holly has made it all the way to Suzie's skirt, and while it's weird to think about it from a normal perspective, Holly has gotten over pretty much all of her hang ups about being this small and the situations she finds herself, so she keeps climbing, crossing over into red tinted darkness as she makes her way under Suzie's skirt. Getting herself into a steady place where the pantyhose meet the panties allows her to prop herself up like she is laying in bed, and she can feel Suzie stop moving as she sits, so she turns on her selfie camera, and the light, smiling as she sees Williams come briefly on cam, nodding to her "Glad you could join us, Holly, we're discussing particle physics today, for the test next week on quantum mechanics, so please take notes, and I will be calling on you at least once, virtual or not" Holly chuckles since particle physics is pretty much her life these days, and if she wanted to, she could shrink down to that scale and probably confirm or disprove some of the stuff in their textbook.
But, Professor Williams asks a question about the Heisenberg uncertainty principle and Holly giggles as she pings him to answer. This principle is something that she knows because it is why no one could find her and her aunt when they first were shrunk: you can know the condition or location of a microscopic particle but not both. Professor Williams compliments her and then informs her that he put her on screen so the class could hear her excellent answer. Holly manages to hide both her amusement and concern, since she is essentially on camera from her best friends panties, though at this scale it likely looks like a green screen background. Class goes on and she doesn't think too much of it, though it was rewarding to impress Williams since he is so hard to please. But, after class: