I was taking some Ms certification courses a while back just for the pieces of paper since I didn't have a college degree. I took their entrance exam and apparently scored in te top 3% so I knew it was going to be a breeze.

I started out sitting near the front of the classroom, but I never really paid attention to the teacher, I worked through the practice book during lectures. This apparently distracted the class because they would come to me for help rather than raise their hand or ask the teacher.

Eventually he pulled me aside on a smoke break and asked what I was doing in his classroom if I already knew what I was doing. I explained the situation and he just laughed. But he did ask me to sit in the back corner quietly and allow him to teach the rest of the class. And I could do my thing until the certification exams.