Connie weighs the benefits of trying to wrest her notebook out of Lelouch's hands against the risks. On the one hand, it was incredibly annoying to have all of her hard work taken out of her hands just like that. On the other, causing a scene just wouldn't do. She needed to be as mature as possible in this situation if she wanted to get an asterisk. And anyways, while she may not have an eidetic memory, she still had a very good retention rate.

So she just sighs, rolls her eyes emphatically at Lelouch, and focuses on committing the rest of the lecture to memory. She could always write down the details later.