Combinatorial explosion of questions and errors
Non-interactive explanations (e.g. textbooks, blog posts, and YouTube videos, in contrast to interactive explanations like classrooms and tutoring) face the problem of combinatorial explosion of questions and errors. As the length of the explanation increases, there will be more and more potential questions a learner could ask, as well as more and more potential errors in reasoning the learner could make (or misconceptions they could have). As the explanation is non-interactive, the explainer must anticipate in advance which questions and errors are most likely for the intended audience, and must decide how extensive the explanation will be.