> If a student fails, they should be motivated to work harder.

Or rather, especially assuming they already work hard, they should be motivated to try different approaches (i.e. new techniques for studying or approaching exercises), and ask for help or guidance if they're stuck. Just working harder does not magically solve anything, in fact it may just mean you double down on a wrong/harmful method.

(edit: this also means teaching people they should not fear asking questions)