Parents at the progressive Waldorf School of Garden City, Long Island, are angry and some are threatening to pull their kids out school because of new mandatory sex education for fifth graders that teaches, among other things, oral and anal sex and masturbation — with illustrations. Part of the new sex ed curriculum, which originated with the Unitarian Universalist Church and is called Our Whole Lives (OWL), was just formally announced to Waldorf parents in March by the school. It includes a controversial book called “It’s Perfectly Normal” that has been around since the early aughts but which parents say...