All three make sense and are principle elements in the Montessori method.
I like this idea:
A math teacher begins each class with a simple question: “Who made the biggest mistake last night?” Then he waits for volunteers to share errors from their homework. After correcting one volunteer’s problem, he challenges the other students: “That wasn’t a big enough mistake. Surely somebody else made a bigger one than that!” With his generous encouragement for learning from failure, he ratchets up his students’ curiosity for process solutions. Revisiting and revising will concentrate the mind if done without judgment.