While in hospital Sadako would make the cranes, inspired by the ancient Japanese story promising a wish to anyone who made 1000 of them. Because of the story, Sadako has since become a symbol for peace across the world.
Teacher Suzanne Russell introduced the pupils to the story and also introduced the idea of making 1000 cranes.
She says it is something she has wanted to do for a long time.
"It relates closely to Maria Montessori, who was a peace activist - it was the focus of everything she did.
"It's quite a big idea, and it [origami] is quite an intricate process. But I am finding it is a wonderful exercise for those who find it difficult to focus."
Pupil Charlotte Mitchell says the first crane she made was "quite hard", but has since made around 20 at home.
She says it is quite exciting the cranes will be going to Japan.
"We are making them because we get a wish and because we don't want any more wars."
Tauranga Montessori Education Trust administrator Laura Rowe says the project has captured the children's imagination.
"Suzanne has been an absolute saint for teaching the children, but once they could do it they ended up harassing people to sit down with them and make the cranes.
"But they have shown amazing dedication and focus - they have to have, because it's quite a complex structure and a huge amount of time and effort has been put into them."
Laura says there is no deadline set for the project's completion.
