Even though your DS was identified very young (age 5?), it is likely that he is highly gifted. Whether he is also a musical prodigy requires more information and time to determine. Your DS certainly has musical talent but a musical prodigy is far more rare. In my mind, it is a wider distinction than that between moderately gifted and profoundly gifted (and I don't mean by the lower DYS standards). The recorder is a very basic instrument and therefore too blunt of a measure to determine the level of his musical ability. Perhaps it would make sense to try him on the clarinet or saxophone or something in the string family and see how far he develops in the next six months. I don't know whether there is an official definition but I personally would not consider any child under age 10 to be a prodigy unless he was at the level of a professional adult. It appears that in most cases, the prodigious ability appears far earlier although without opportunity . . .
