I would advise trying to obtain some OFSTED reports which are available online and cover week-long observation of schools in the UK by examiners to ascertain the quality of teaching. They point out downfalls and suggest strategies to enhance learning.

One particular example that I found was where a teacher was praised for identifying 3 categories of child and splitting them up according to intelligence. The group with the higher intellect were left with tasks to complete by themselves, the teaching assistant took the mid-level students and the teacher herself looked after and directed the lower tier children. The group with the more competent children were also set more demanding challenges once the first set of tasks were completed.

I personally think that this is a great way to teach and there are too many instances (particularly in the schools that I went to) where the teaching staff focus primarily on those of higher academic ability in order to fulfil these students' potential whilst almost ignoring the fact that half of the class are not given the attention and guidance they need to excel themselves. It creates a massive gulf between those of differing abilities and may also be a cause for the increased levels of truency and delinquency amongst teenagers if their needs were not met satisfactorily in their younger years (that's my theory btw, and not scientific fact! )