It goes against the conventional teacher wisdom that says students have to handle abstract ideas, and what the heck does writing physically have to do with that?

Accordingly a great orator has truly said that "an eloquent man must speak so as to teach, to delight, and to persuade." Then he adds: "To teach is a necessity, to delight is a beauty, to persuade is a triumph."(2) Now of these three, the one first mentioned, the teaching, which is a matter of necessity, depends on what we say; the other two on the way we say it.