As an aside -- is California that different from the rest of the country? I always thought that 8yo were typically in 3rd grade out here, so I'm caught off guard when reading stories like this, with a 8yo in 2nd. I can't imagine the frustration O.P.'s son must be faced with as a 151 8yo in 2nd grade.
Dandy
FWIW, most kids here are 7 when they start 2nd grade and turn 8 during the year. In our area, the cut-off date for kindergarten (which affects all of the rest) is 5 by some time in October. I know that in some parts of CA where we have relatives, it is 5 by some time in December. Maybe you live in an area with a later cutoff date or have a kid with a summer birthday?