The children had watched the whales from Cronulla, Jibbon Beach and Cape Solander as they passed up the coast.

But when their teacher Catherine Lee spoke about preservation, Ethan had an idea.

Ms Lee said he called out: ``I know! We can send a postcard to everyone around the world to tell them: If you want, you can join in and tell the Japanese not to hunt down whales anymore. Because we want the whales to stay healthy and strong and they're gentle creatures and we don't want them to become dead or extinct ever like the dinosaurs.''

The Oyster Bay preschool created a petition and Ethan and his classmates have worked hard to collect signatures.

``Children have collected signatures from family, friends, neighbours and the wider community.'' Ms Lee said.

``I spoke at a recent Sydney Environmental Educators Network conference and many of the participants at the conference signed Ethan's petition.

``Jerry Coleby-Williams, a [Queensland] presenter from ABC Gardening Australia, also signed the petition and wrote to Ethan to thank him for his initiative.''