You can get some older NWEA national norming criteria online, but the most recent is not available to the public. The most recent nationa norming criteria "downshifted", apparently, with similar scores representing higher percentiles when normed nationally.
From 2011 norming criteria,
Winter Math 210 is equivalent to 97th percentile for SECOND grade
Winter Reading 190 is 93rd percentile for FIRST grade, or 73rd percentile for SECOND grade.
In my experience, I would request the school for subject acceleration in math only by placing him in a 2nd grade classroom **immediately** for math, and next year, a 3rd grade classroom for math. Math is difficult for classroom teacher to differentiate, but reading is not so difficult and he'll get better instruction staying with age mates.
I chose subject acceleration for my son, who is now 9 - 4th grade by age. I used NWEA national norming to drive acceleration choices. When his NWEA test represented 90th percentile in a grade, I bumped him to the next. My son is now doing high school level work with college level reading.
My son's 1st grade scores were nearly identical to your son's. My son had 211 for winter math. 3 years later, he's doing Algebra 2. Excuse me while I go hyperventilate a little bit. LOL. My son's IQ is not particularly impressive - just above Mensa's cutoff, but he hated the social parts of school and loves learning material in depth. He hung out on community college campus and made friends there with students. He enjoys activities like swimming lessons with age mates, and he enjoys Minecraft and Star Wars, but he's mostly annoyed by agemates and consumerism. He's a much more relaxed, calm, and outgoing person since following his academic needs.
