Research in cognitive science proves that the most effective way to teach new skills is to put learners in the kinds of situations in which they need to use those skills, and to provide mentors who help learners when they need it. Learners come to understand when, why, and how they should use target knowledge and skills. They receive key lessons just-in-time, at the exact moment when they need to know the information, when it will make the most sense to them, and in such a way that they will be most likely to remember it later when they need it most.