Book Week I like this as a starting point for the book to have kids visually state what they think is better meat or fruit and veg. Could be then used after the book as well to discuss Brian vs other piranhas.
This is such an awesome website to help teachers plan debates for their class depending on the content area. It lists rules, roles and evaluation forms! Could be helpful with understanding persuasive writing, author's purpose: to pursuade, etc
I would use these journal prompts when students are learning about persuasive/opinion writing. Using these prompts in a dialogue journal will also give the teacher a chance to ask questions to expand the student's point of view.
Here's an Entire Collection of Stimulating Debate Topics for Kids