Knowledge is not the same as understanding, Both are suitcase-words that avoid strict definitions.
An example: Newton's laws of motion are quit easy to remember and know. The concepts of force, mass, and acceleration might seem trivial, and engineering students are expected to fully understand the concepts after one or two lectures. Isaac Newton himself probably spent years pondering before he understood the concepts and their relationships.
One should not be surprised of numerous structural failures.
I see that there is a spectrum: remember - know - understand where the boundaries are blurred and there are several layers.
The best starting point I have found: How to Explore the Difference Between Knowledge and Understanding