Comprehensive Sex Ed (CSE) is now a requirement in California's middle and high schools, so there's not much districts can do about it. The law requires that certain subjects be taught, but fortunately does not specify how these subjects must be taught or how to balance each of the required subjects. But this isn't all bad. School districts now have an opportunity to create a curriculum that is even better than what was previously being taught in their schools, if they will take the time to create it.
For example, abstinence is one of the subjects required by the California Healthy Youth Act, and yet most CSE curricula available off-the-shelf barely even mention it, let alone fully explain the myriad emotional and physical benefits of it. If school districts are really interested in the best health outcomes for their students, they will take this mandate (given to us in the California Healthy Youth Act) and dedicate a sizable percentage of class time to this most important topic which many youth don't even realize is a viable option.
An assessment of all current research on the effectiveness of Comprehensive Sexuality Education (called Re-examining the Evidence by Stan E. Weed and Irene H. Ericksen) reveals that this Risk Avoidance approach has done more harm than good. It also reveals that curricula that place greater emphasis on abstinence show the most promise for producing positive outcomes.