It works well more for the feeling of achievement. If you've seen America, you should have noticed that lifestyle and standard of living is more important than educational achievement. This is the truth. A foreign student will do better in math, statistically, but poorly in English. Language skills will always be native and non-native. The latter will always have to struggle. Language proficiency, however, occurs through cultural development. Thus, exclusively IQ-based placement will place performance assessments and industry above cultural development. Either one in exclusivity will cause social problems in both the nation, the communities, and individuals. The balance is never achieved; it, at best, can only be sought. You think Germany is great, but what about many [perhaps wrong] attitudes around the world that it is the domain of elitism, Nazis' breeding-grounds, and a narrow-minded superiority complex? If any of these are given even slight credibility, it shows lack of cultural development. I think Germany is great, but attitudes have a foundation not in IQ-results, but in cultural development. Thus, not all that works in Germany can work here.
If something like this was put in, there would be a lot more descrimination, a lot more, anger and hatred, and a lot more fights in general due to the very nature of this would be borderline if not complete descrimination since i do have friends that arent the smartest but they arent bad people and shouldnt be treated as such and i know they would hate being treated like they were an idiot or something worse.
Schools should not be divided by IQ levels it would cause other students with lower IQ's to feel bad about themselves which could result in a, "what is the point" attitude. It is important for everyone feel the same and be able to see their strengths not just their flaws.