Perhaps they were taught about it, but did they learn it?

Have they retained that knowledge beyond the test at the end of the semester?

Anecdotal observations would imply that they have indeed been taught it, and indeed have failed to retain the concept.

I have no rigorous data regarding either; but the generally poor outcomes which appear as result of a lack of retention of scientific, math, socio-economic, and anthropological instruction do seem self evident both from within and outside of the US, in headlines and actions, writ large and for all to see.

Is the problem the use of teaching methods which focus on short-term memorization rather than conceptual comprehension? Is it the lack of support for instructors? Is it a lack of focus in the student body? Is it some or all of the above in varying degree? Or something else entirely?