They used a similar system in NYC grade schools, but when I was in 5th grade, they decided there was a stigma involved, so they assigned class numbers randomly. Since practically all of the "smart" kids had been in 1-1, 2-1, 3-1, and 4-1 together, sticking them (okay, sticking "us") in class 5-3, while putting the future democrats who had previously been in 1-6, 2-6, 3-6, and 4-6 into 5-1 really didn't fool anybody. An early attempt at political correctness, way back in 1958.
i think they did away with the tracks in my pub school also for the same reason. it’s amazing they let this gifted and talented stuff go on today because what does that do to the self esteem of the ungifted and untalented? I guess because i live in a hypercompetitive world where everyone competes through their kids [and OY the christmas letters that demonstrate that!] the whole idea of it seems like more ammo for people to use to brag about their kids.