In-class differentiation means that the whole class is disadvantaged, because they cannot experience an ordered classroom where the expert instructs them. They cannot experience a coherent curriculum because the curriculum must be personalised.
But there is a huge difference between in-class differentiation and targeted support outside class. Schools such as Michaela, for example, target pupils who need it with an intensive synthetic phonics programme. This is because they recognise that without these fundamentals firmly in place, pupils will not be able to access fully the rich knowledge curriculum that they offer through whole class instruction.
Or consider the example of Japan. Large mixed ability classes receive whole class instruction, and they are all expected to reach the same standard. But teachers regularly give additional support to pupils outside lesson time. They are able to do this because they teach far fewer lessons per week due to the large class sizes, and because they are not wasting time producing complicated, ineffective plans for different activities within each lesson.
This is the best model. Coherent, whole class instruction in orderly classrooms, with the expectation that everyone will master the content, combined with targeted support outside the classroom, made possible by an efficient whole school approach.
In the madness and chaos of differentiated classrooms, with exhausted teachers and the noise and distraction of multiple activities, those who need additional support do not get it. In the orderly, sane world of a coherent curriculum and whole class instruction, there is plenty of time and energy to give them the extra help they need.
Whole class instruction enables targeted support. Differentiation damages everyone’s progress, but like all ineffective approaches, it hurts the disadvantaged most of all.