The learner, child or adult, his experience, his interests, his concerns, his wonders, his hopes and fears, his likes and dislikes, the things he is good at, must always be at the center of his learning. He can move out into the world only from where he already is in. - John Holt
Inspired by writers like John Holt, Daniel Greenberg, and Malcolm Knowles, I have come to the realization that the best learning is most often self-directed. That doesn't mean there is no structure, but instead, that the learner bears primary responsibility for structuring their learning. The learner can decide what to learn (within the parameters of the course and context), how to find resources, and even assess their own learning. The "teacher's" job, then, is to facilitate and to guide - to step in when the learner wants or requires it, and to stand back when they don't.
Towards that end, I employ self-directed learning projects in several classes I teach, where learners are afforded several weeks of in-class time (in lieu of any formal curricula) to choose projects they want to work on. They can generally choose anything that interests them as long as it aligns with course goals, and are responsible for checking in with me (in writing and in person) during their projects. Once comlpeted, students exhibit their projects to their peers, get (and give) feedback on each other's projects, and grade their own projects based on their experience with the project and feedback received.