Deep down, Jo Hirst had been anticipating these questions. And she knew she had to get the answers right.

It was bedtime, and her six-year-old was curled up on her lap. Assigned female at birth, from 18 months of age Hirst's son* had never wanted to wear female clothing and always played with boys.

He refused to answer to the name he was given at birth, instead rotating a handful of male names he preferred.

At kindergarten, with no uniform or sex-segregated toilets, it was easy enough. But when he arrived at school Hirst was dismayed to see her gregarious child became withdrawn and miserable.

"When he told me he was a boy - and it took a long time for him to be able to do that - I realised he hadn't had the language to describe what he was feeling," says Hirst.

So she scoured the internet for information, made contact with the gender service at the Royal Children's Hospital and joined Gender Help for Parents Australia, a support and friendship group for parents of transgender and non-binary children.

But despite a wealth of information for adults, she was unable to find a suitable resource for her son.

A teacher and storyteller herself, Hirst decided to write her own. The Gender Fairy is her new book for very young transgender children to read with their parents or teachers, the first book of its kind in Australia.

On Tuesday the Minister for Equality, Martin Foley, launched the book at an inner-city primary school*, with Hirst and 10-year-old transgender girl Evie. Evie told Hirst that if the book had been available when she was in prep, she would have had the language to tell her mum about her gender identity much sooner.

The Gender Fairy begins with a story of gender stereotyping: two babies who are born and bought presents in pink or blue. And the gender fairy  (who is non-binary) answers questions for two young transgender children. Can I use a male toilet? (Yes, you are a boy). Can I wear girl's clothes? (Yes, wear the clothes that make you feel comfortable).

"I wanted to write a book where the children can realise they are normal, they are not alone, something that would teach all children about gender diversity," says Hirst

Last month Australian Senator Janet Rice, whose wife Penny Whetton is a climate scientist and trans woman, talked about Hirst's picture book in the Senate. Her comments were part of an address marking the transgender day of remembrance, a tribute to transgender and gender-diverse people killed due to violence and prejudice.

"Jo, I congratulate you on your book and thank you for your contribution to improving our collective awareness and understanding of what life is like for some of our younger transgender members of our society," Senator Rice said.

Dr Michelle Telfer, the director of the Royal Children's gender service has written a foreword to the book. It also has notes for teachers and parents, compiled by La Trobe University's gender expert Roz Ward.

Hirst's son, successfully underwent his own "social" transition in prep, with support from his school and the Safe School Coalition.

He now expresses himself as his true gender; wearing the clothes he feels comfortable in, using the boy's toilets and a male name he has chosen.

*Some names and locations are not disclosed, to protect privacy.