That is not what I ask :)
I'm only gathering ideas, from a competent community ; that fits completely in this homework frame. Moreover, I don't ask you to write this lesson for me.
I'm more interested in "if it were for you, what would you like to do ?" What could be a good or efficient or fun way to learn the Blockchain ?
Fun? Maybe an illustration into the Byzantine General's problem.
But efficient? I think it's a complicated enough idea that it'll require a bit to outline the problem it solves and then longer how it goes about solving it.