Sorry it didn't work out, but in a few years this will be a distant memory. Is this your eldest/only? I know I worried over stuff like this when my kids were younger, then it didn't seem so aggravating when they were a bit older.
How they treat a younger kid is a legitimate concern. My 4th grader DD9 went to a different school this year, different school bus - kids on the bus gave her a bad time at first for sitting near the back - kids thought she was a 1st grader. Middle kid had similar experiences, but is now normal height at 16.
There may also be some legitimate legal concerns. Day care centers have to maintain certain student teacher ratios based on age. While this may not be the case at the library, and while I can't imagine how you might get hurt at a math class, if he got hurt and the insurance company stepped in, it could be a problem if he was significantly younger than the advertised class age.
As for some folks commenting on sports and age, I don't know how many parents I see trying to get kids on 18U teams when they are 14 for the college showcase exposure. In most cases, these kids are very good, but not DI stuff. I personally have seen kids lose out on opportunities because they want to be on the older team. It is different in sports than in academics. In sports, you want to be one of the best on the team. That gets you playing time so you can be seen and so you can improve in game situations. Being average on an older team means holding down the bench. Sorry for being off topic, but just wanted to note the difference.
