Category contradictions

I have been reading several books about educational reform and charter schools (e.g., Disrupting Class). I began to experience a vague associated with a topic I used to cover when teaching educational psychology. One persuasive logic in individualization is that categories of learners can be identified and then taught as most appropriate for that group. Students and their parents should be allowed to select approaches that best offer the best categorical fit.

The association I flashed on was the logic for ability grouping. The notion was that if students were grouped by ability instruction could more precisely be targeted to each group. Now, if I remember some of the research findings accurately, whole class ability grouping improved the achievement of high ability students, but diminished the achievement of low ability students.

Sometimes logic when put into practice does not work. Then, it is time to re-evaluate the logic. My logic in explaining the data to the students was that in group learning situations all participants serve as teachers. Take the high aptitude students out of a group and the remaining group experiences a lower quality of instruction.

I wonder if a similar phenomenon applies with other categorization systems. What may be an advantage for one category may well be a disadvantage for those not fitting in that category. In fact, what those not fitting in one category may really need is the presence of a group that could be removed. 

Aside from ability grouping, I wonder about other categorization variables. I wonder if most are not really proxies for motivation. Removing the more motivated students from a group does not mean that those who remain would now be easier to teach.

The idea of to each his own sounds great but the idea of categorization has to my knowledge generated few positive outcomes for all involved. I would be pleased to modify my position given good data to the contrary.