...there is not a "top" or a "bottom" or a "better" or a "worse" here.
Well...yes, there is.
People who are gifted at anything are generally better at learning it or doing what they're gifted at than most other people. This is the definition of giftedness. A major problem in education is that schools are more likely to claim that cognitive giftedness doesn't exist than any other kind of gift.
IMO, differentiation doesn't work because our education system has made a decision not to address the needs of gifted kids. NCLB is all about students who fall behind. There are exceptions, but IEPs are generally designed for the special ed. population or for students with disabilities. Etc.
Teachers can reasonably claim that they have too many students to be able to provide extra teaching on new topics to one or two gifted kids. Fair enough. But they could send these kids to another grade for subject acceleration or whole-grade accelerate them, but many schools flatly refuse to do this.
Many educators don't understand levels of giftedness or gifted learners, but all they have to do is read a book or visit a few websites to get all the answers they need.
Again, it's a decision they've made, whether they'll phrase it in those terms or not.
