At what age is sex education taught?

There's no single answer to the question of at what age sex education is taught, as it varies significantly by country, state/province, and even individual school district. Some countries introduce basic concepts of puberty and reproduction in elementary school (ages 5-11), while others wait until middle or high school (ages 11-18). The comprehensiveness of the curriculum also varies greatly. Some programs focus solely on biological aspects, while others include information on relationships, consent, sexual health, and avoiding risky behaviors.