"They learned about the elements that make a good story, and discussed and worked on their story shape to give their writing an opening that hooked the reader in, built to a climax and resolved satisfactorily," Mr Bonallack said.
The pupils also "sharpened their climaxes with short punchy sentences, and discovered how to use strong verbs and invent original similes", Mr Bonallack said.
"Over the two days - with the help of a large jar of jellybeans - they each wrote, edited, polished and shared a story.
"I've done a lot of workshops for teachers and other adults, but never for children.
"When I was asked to do two full days with 16 children, I gulped. Frazer said they were gifted, but I couldn't imagine kids focusing for two days solid on writing. But gifted they are and focus they did.
"I was blown away by their involvement and by the quality of writing they developed."