Schools offering sex education are now free to directly address issues of consent, coercion and sexual diversity.
The Ministry of Education has released its updated sexuality education guide, produced in consultation with schools and health experts.
It is the first update in more than a decade.
The ministry said the changes will help encourage problem-solving and decision-making for students in relation to sexual activity, as well as assertiveness skills and the ability to identify pressure from others.
It said schools were free to decide how they teach the courses in consultation with their community.
Family Planning said the changes were a positive step toward a more holistic view of sexuality education.
Its director of health promotion, Frances Bird, said the new guidelines were clear and inclusive, and recognised key social issues such as pornography, social media and consent.