BS! You don't have to teach a child under the age of 6 what these perverts will do to them or what's ‘inappropriate behavior’.
“Stranger Danger” works just fine!
I will digress from the main topic to tell you that you are incorrect. Most predators are related to the child, or have a close relationship with the family. So Stranger Danger is an incomplete message and may actually thwart your child’s ability to find help from a “safe” stranger if separated from you in public. Read “Protecting the Gift” by Gavin De Becker for a good inroduction.
Children need to be well-informed by their parents/guardians, not by Government Schools.