@WhatMom, Keep your son talking by reinforcing him with "That's a great question... what makes you ask... " etc in a casual conversational tone. Especially feel free to share with him when you do not know or are not sure of the best answer to something he may ask about, and reassure him that you can look it up together and learn more together. This may encourage him to take it in stride that different people know different things and learn them at different times (at younger or older ages) depending upon their individual circumstances and experiences which happen to bring a question to mind. Instilling this mindset or worldview may help him with many future situations in which he may be way ahead or even possibly behind his cohort in becoming aware of different things.
PG kids may be more asynchronous in their development, and being accepting of this (not feeling a burden that he must consistently know the most) may help him skate over any real or perceived gaps with a strong sense of self-acceptance as well as acceptance of others (not feeling thin-skinned or picked on or excluded by any difference because he will realize that having differences is a universal experience which everyone encounters to some degree).
You may also wish to read everything you can in the Davidson Database on grade acceleration. There is very good research and guidance.
