He can sit with Ben, that's fine, although nobody will mistreat him. Lyla and I keep a good eye on my classes and the kids know that. He won't need a slate, I don't even know what that would be needed for. Why does he need a rock? If he's poorly-behaved, I'll talk to you both about it. There might be an issue with no computers/technology, though. The kids don't use them to work with, but it's best if I use one to project what we're learning onto a screen. My handwriting is not the most legible, I've been told. Although Bruno Madrigal is also going to be teaching in this class, if that helps, and he's from the 1950s so computers are new to him as well. I don't know how neat his handwriting is.
25ml is about 0.85 fluid ounces. And yes, I'll only use your blood for the specific purpose of working on the cure for Sirius. It's all covered in the paperwork, don't worry. I can print you off a copy of everything if you want to read through it, even before you make a decision.