"There are many schools who don't really know what to do or how to do it, so what this resource allows is to give a lot of information at the beginning for teachers, and then it allows them to look at the lessons and make it their own."
The guidelines gave age-appropriate standards for each lesson.
Family Planning health promotion director Frances Bird said children were exposed to far more adult material than earlier generations.
"Young people are exposed to more and more sophisticated ideas and they're not able to unpack it, so we wanted to start young, build on it, get them feeling confident and comfortable about their bodies, their own sense of themselves and what's OK and what's not OK, identifying those sorts of feelings in their bodies as well."
New Zealand Principals Federation president Philip Harding said there could be "pushback" from parents who felt they had not been consulted on the new guidelines, which are not part of the New Zealand Curriculum.
He wouldn't be surprised if parents said: "Excuse me, this is our right to hold these conversations with our children - if and when they are needed."
Pasifika Principals' Association president Unasa Enosa Auva'a said any discussions around sexuality and relationships "cut to the heart" of Pacific families. "From a Pasifika point of view, this is an issue for our parents. Our parents need to be involved in teaching their children, particularly at the primary level."
What Year 1 students will learn
• Working together as a class to create a safe classroom environment
• Discussing the meaning of respect and showing respect for others
• Describing themselves and their relationships with others, including similarities and differences
• Describing themselves in relation to their gender
• Exploring and sharing ideas about friends and classmates
• Using 'I' statements to express ideas and feelings
• Identifying body parts, including sexual parts
• Discussing changes to the body and ways to care for the body