to find synonyms for "boring"? For a child, that effort requires remarkable intellectual gymnastics, some adults can't execute such an effort.
One of my brother's granddaughters is getting tested for ADD. She is in kindergarten and acts out in class. I really have not spent a lot of time around the child because I have my own life interests, but the times that I have, I have found her to be of remarkable inate intelligence, she only has to see or be shown something once to pick it up. She asks rapid-fire well thought-out questions for her age. I am not sure why she acts out in K-school, in my estimate, it isn't because she doesn't understand. I mentioned diet to my brother with the idea that she is missing some nutrients, I still may suggest to him that she get a blood analysis. But after reading your post and thinking about my own observations of her, maybe the issue is when her teacher explains stuff, she picks it up really fast and gets bored when the teacher explains to other kids. I know that I have always been a slow reader, I got smoked by kids in speed reading exercises in grade school, but I successfully became an engineer and it was only a few years ago that I realized that eventhough I read slow, the absorption level of what I read is almost total, I can give a pretty vivid synopsis of anything that I read, and an added bonus is that slow reading for an engineer is not a drawback because of the complexity of my work demands slow reading to get through the dense research reports that I read. So intelligent people arrive in different ways.
It is good to see creative teachers like you in the classroom, teachers that see each kid as a unique canvass and not a pressed out duplicate of some ideal student. You can craft teaching to each individual kid, I only wish that administrators have enough foresight to give you smaller classes, or assistants.