It sounds like you're doing a great job advocating for your child's educational needs, but are facing some challenges due to the diversity of abilities in his classroom. Consider setting up a meeting with both teachers and perhaps even the school principal or a guidance counselor. In this meeting, discuss your concerns and ask for specific strategies or resources that could be used to challenge your child at his reading level. You may also want to explore additional options outside of school, like advanced reading programs or clubs, online resources, or local libraries. It might also be beneficial to have your child tested for gifted programs in your district, if that hasn't been done already. This could open up more tailored opportunities for his learning.
