Originally Posted by spaghetti
I don't know how to remedy the situation.
Some do.
That is to say, Total School Cluster Grouping has been found to be effective:
Originally Posted by NRC G/T Spring 1996 Newsletter
During the 3 years that students were involved in the cluster grouping program, their achievement increased significantly when compared to similar students from a school that did not use cluster grouping. Additionally, during each of the 3 years of the program, more students were identified by teachers as high achieving, indicating that not only were achievement scores increasing, but that teachers were identifying students who were not initially recognized as high achieving. This may be due to the fact that high achieving students were clustered in one classroom, thereby allowing students in other classrooms to be recognized as high achieving. It is encouraging that not only did the identification categories of many students increase during the 3 program years, but that this was followed by an overall increase in achievement as measured by the Iowa Tests of Basic Skills.

The implications are that when a cluster grouping model is implemented, there may be a positive effect on the achievement and identification of all students, not just those identified and placed in the cluster for high ability students.
These are not new ideas... this was published in 1996, twenty years ago.

Originally Posted by spaghetti
But so far, nobody has found a way to set appropriate expectations that don't have associated bias.
1- In the context of this discussion thread, the expectation that 15%-45% of students need or would benefit from advanced curriculum is based upon test results.
2- What source(s) inform your belief that "nobody has found a way to set appropriate expectations that don't have associated bias"?

Originally Posted by _Angie_
In our school they told us the teachers are not allowed to teach above grade level. So even if they can cluster group the kids they can only do extensions on the current material.

Someone actually codified that rule into the district's rules. Why?
To close the achievement gap, and give the appearance of equal outcomes for all students, regardless of readiness or ability.