Writing about things you are still learning would probably be a great idea, actually. It would likely help you learn them better (research shows that in peer-to-peer tutoring, the tutors benefit more than tutees). And you can always leave in placeholders that give you more to write about: "I don't know why this is yet, but I'm going to look it up and write about it later."

You might also have an unfair advantage, in that since you have newly learned it, you'll have a better perspective from which to explain it to people who aren't familiar with the material.