I went to this school several years ago and I remember I spent almost all my time in my colour group. At lunch time I would meet new people and learn that just because someone was a lower colour than me (I was Violet) it didn't mean they were dumb or boring or anything negative. I spent my time hanging out with those of other year groups too, I still have friends to this day from years above and below me and my now boyfriend was in a different colour group to me.
It is important that people learn that you need to interact with lots of different people, not only so that they improve their social skills and friendships, but so that they know how to talk to different people in the work place. If you tell someone "You can only spend time with the people we think you are as intelligent as" you will cause a multitude of problems. Those in higher sets will learn that other people are inferior than them, therefore they don't need to spend time with them and lower sets will have the idea that they aren't good enough reinforced once again.
This is a preposterous idea and I hope that the school does not implement it.

#12: -

its not the colour groups but house groups eg wonder,bustle etc but your point is very valid thankyou