Shayer & Adey in their book "Really Raising Standards" make a good point.
They do not know whether there has been a real drop in education, but they
do know how to raise the thinking skills of students. They then detail the
concepts, and the results of their research. The result is a substantial
increase in performance of all students by implementing their method of
cognitive enhancement.
Despite all of the calls for raising standards of schooling, hardly anybody
seems to be looking at the research which shows that individual student
thinking ability can be raised across the board. Once this is done scores
on the state tests should show an increase, the same as the English exam
showed an increase for schools that implemented "Thinking Science".
There are similar programs that have come and gone in the US such as ADAPT,
despite proven ability to improve student performance.