I can recite the quadratic formula. That flashcard was stuck on my wall for up to three months leading up to my GCSEs, engraved into my memory ready to recall and apply to a question that may or may not come up on my maths paper 2. Funnily enough, it did come up on my paper, and I was prepared to answer it, however, there are a whole host of things I have never been taught. Something that will never be on an exam and that no amount of revision notes blu-tacked to my wall will prepare me for.