Have you considered that your mind was not able to keep the content of your courses for the very reason that it won't link it to precise uses? For example, let'

Have you considered that your mind was not able to keep the content of your courses for the very reason that it won't link it to precise uses? For example, let's imagine you want to learn the Pythagorean theorem. You may learn that the square of the hypotenuse is equal to the sum of the two other sides by heart, and hope it will stay in your brain until the 8th grade (but it's probably too late now). Otherwise, you can try by yourself to know a way to find a relation between the two shortest sides and to the hypothenuse, and eventually find out the Theorem. Then, you can be sure you will remember it longer. Why? I have my theory, based on Spinoza's ontology. It's a bout the three kinds of knowledge: 1st kind: You learned something from someone who told you, an erroneous deduction, or even experience. 2nd kind: You learned by demonstration, you KNOW why... 3rd kind: Your knowledge of the full system lets you deduct theorems, intuitivey. Of course, the third kind of knowledge is not what I am talking about. It is the second kind that will interest us, as the knowledge of the third type is a lifetime exercise.