Oh Sweetie!
what a mess! I would ask the school that exact question and ask them to look for a tester who can use tests such as SBV that can be used on a wide variety of ages. I don't know of any tests that can generate a number without an age - did they do the scoring against 6 year olds or against 16 year olds? If they 'pretended' we was six then the next step is to give him academic content that is aimed at a bright 6 year old.
But, back to the original question - why is it hard to keep him on topic. I would say that no test is as good as good old fashioned trial and error - if the idea of giving harder material worked in the testing situation, then maybe it will work during circle time as well.
Does the school have a classroom for 6 or 7 year olds who are bright? That might be a good place to try a trial placement. Another alternative is to bring 2nd grade material to your son's classroom.
Best Wishes,
Grinity
