Teaching Zoroastrianism? Here's great short article that explains it's basic beliefs and rituals and why the author thinks the religion might not survive.
Zoroastrianism, the world's oldest monotheistic religion, might be the least inclusive of all religions. It numbers less than 150,000 and for every birth there are five deaths. For these reasons, Ariane Sherine suggests that "Zoroastrians need to widen their admission criteria fast, or go the way of the lesser Antillean macaw and the koala lemur."
Sherine, writing for The Guardian, writes that as a child, she was was never allowed to take part in key rituals or even call herself a Parsi because she is the daugher of a female Zoroastrian in a religion that is patrilineal. That makes her membership doubtful.