Our state is uncomplicated, so this is coming from that perspective.
Determine your grading scale, first.
Determine what things you will grade, and document. I.e. written narrations, essays, tests, quizzes, field trips (with some sort of written follow up); bios, specific curriculum finished.
watch a documentary? Have her/him orally or write a narration, timeline maintenance.
Determine a rubric or outright grade for those various things, determine what percentage they will be worth (you could probably clump a few together) and then average out the grade.
HTH.