Birth education
Let the child know that he was born in his mother's belly, not picked up in the trash can.
Gender education
Educate children to know their own gender. Boys have penises and girls have pudendal parts.
Cognition of private parts
Tell your child which parts are private, and you can't show them to others at will, let alone let others touch them.
Behavioral boundaries related to sexual organs
Teach children to keep their hands clean when touching genitals.