Things to consider: "Knowing" is a vague term as knowledge is not defined, and therefore there is no metric to measure against. The way knowledge is assessed and reported is also inconsistent and variable.
Are methods of learning clearly definable? The question assumes so, but many methods of characterising student learning styles, behaviours, idiosyncrasies etc have been called into question and disproven.
Assumes student is fundamental unit of education and does not consider either multiplicity of origin, nor alternatives (where education is a complex process).
Assumes differentiation is necessary for student development- is it as pivotal as generally good pedagogy, content delivery and exercises?
Teachers may know students and their learning patterns but struggle to deliver even with this knowledge.