When you are in high school, memorizing seemingly useless facts only to forget them as soon as the test is passed, you never dream that you will need the information again. Years later, you find your son heading down the same path.
Now, however, you are wiser. You know that the key to memorization is understanding. And so you bone up on the material so as to pass on your new-found wisdom to your son.
Of course, first you kick yourself around a bit until, finally, you find forgiveness for not learning it right the first time. Then you pray that the next lessons-not-learned will be a tad bit easier to grasp the second time around.