Please speak to school. Please include your son in the discussions so he feels empowered.
He has done nothing wrong and was right to tell you. He has told you in an innovative and clever way, he is a bright child. he is probably feeling low at the moment so make sure the rest of life is nice, good tea or treat out if you can afford it.
Maybe give the chance to chat in private with you while doing something else, cleaning his bike or whatever, rather than sitting him down and saying right we need to do XYZ....
You could either treat it as any other kind of bullying, which should not be tolerated (get a copy of the school anti-bullying policy, if they have one, which should be on their website. get copies of the government policy...
[[https://www.gov.uk/government/publications/preventing-and-tackling-bullying]
Take a look, go into scool, report it etc.
Or you could go down complaining about the specific nature of this bullying. I am not sure what would be better.
I have no idea why persecution of ginger-haired or red-haired people is not considered racially motivated. It must be taken just as seriously as it were.
If the school will not take it seriously you can read up and make sure they do! Whatever the reason for bullying, it is wrong.
news.bbc.co.uk/1/hi/6725653.stm
riehlworldview.com/2013/04/congrats-redheads-youre-officially-a-protected-minority-and-a-victim-and-the-eeoc-and-nypd-agree.html
www.telegraph.co.uk/news/celebritynews/9788039/Bullied-and-worse-for-being-ginger.html
Good luck, please tell us how it works out and give the wee lad a hug from Mumsnett! 