John
I am 76 years old & found I was PARTIALLY colour blind during WW2 at age 18 in the Royal Australian airforce.To the best of my memory I had no trouble with my schoolmates. During my life the colour problem has restricted certain trades (electrical, pilot, train driving, colour decisions etc) but otherwise no problems, just a bit of a nuisance. It sounds as if your son is also PARTIALLY colour blind as FULL colour blindnes I believe sees only grey. I suggest he says nothing to his school mates & if it comes up just tell them he has something wrong in his eyes that a lot of other people have and really " it's no big deal!" All the best