I guess you should seek out solutions with the teacher if your kid is too advanced to fit into what’s being taught. Even in US, teachers usually don’t like kids disturbing the class. My US friend’s child is extremely smart and is very advanced in math. He is in 3rd Grade but is placed in a special class to study 5th Grade math. I guess even that is too easy for him. He often makes noises and his parents get contacted by the principle of teachers. It’s still a problem. My son goes to school in Shanghai. I asked if he feels boring in math at school. He said no. As for math, his school groups the kids in his grade into 5 levels and teaches them at different levels. When they do exercises, the teacher usually assigns a lot and keeps every kid busy. Even within the same level, the teacher sometimes assigns different homework based on the kids’ capability. I think if the content being covered by the teacher fits your kid’s level, the problem shall be resolved.