I remember that my child's K PS teacher spent 8:00 AM - 8:40 AM (class starts at 8:40 AM) for several weeks to read with one child who was "at risk" because of his inablity to speak english. When we asked her why this child got extra instruction with her, she said that she is allowed to help students "outside the school program" in both ends of the spectrum and she chose to help struggling kids with her time before classes start so that she does not have to do pullouts at class time. There was no "program" for what she was doing and there were no rules and requirements - the teacher did this on her own and applied her own judgement on who was to receive her time and enrichment.
I believe that this could be the case with this secret program in your son's school - it could be that she thought that these loud kids would become manageable if they were given more enrichment and went out on her own to challenge them in math. So, this program may be done at teacher discretion, not open to all kids and not based on any criteria - it is not a fair situation, but there are programs in most public schools that the teacher has full jurisdiction on.
I am sorry that your child feels left out. If I were that teacher, I would be happy to take such an eager student into my special math enrichment class.
