[Ed. Note: This image, "The Learning Pyramid," is NOT based on any verifiable research; perhaps, no research at all (see this and that). This pyramid is widely cited yet it is, as Christopher Harris shared in an email, a hoax. You can learn even more about the origins of the Learning Pyramid hoax here. Nonetheless, I stand by the idea that the marriage of teaching and content creation is a powerful pedagogical practice (see this).]
(Fictitious) research from the National Training Laboratories in Bethel Maine summarizes the impact different teaching strategies have on learning retention rates.
Anyone who has ever had to teach anything will tell you that teaching others leads to the deepest learning and greatest likelihood that the content being taught will be retained by the "teacher."