Originally Posted by Minx
I am working with the school to accelerate him two grades
Are you comfortable sharing what this double-skip is based on? Iowa Acceleration Scale? Having older friends? Strong portfolio of accomplishments? High achievement test scores? Teacher recommendation?

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Processing Speed (PSI) 88 (21%)
Some may see this as a red flag. Does he process what is being taught in a timely manner to stay on task? Finish tests within allotted time? Keep up in class so as to not disrupt teaching pace and slow down the class? Would he be able to compensate for any possible speed deficit amongst students 2 years older? If there are shortcomings in processing speed, while they could possibly be accommodated in the classroom, they may not enhance social relationships amongst new pupils 2 years older and the ability to make friends when introduced to an older cohort; Rather the older students may believe they are moving slower for him because he is younger.

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I am wondering how to best help him.
You don't mention especially what it is you wish to help him with. Many parents upon learning their child is gifted want to be prepared to help their child in a general sense. You may wish to get and read the book "A Parent's Guide to Gifted Children".