This type of talk is presentational rather than exploratory and with that comes a range of different skills.
There are a range of things to consider when deciding whether to have a debate in class. Firstly, there needs to be a variety of viewpoints or sides of an argument to be debated. Then you need to consider if the children have enough knowledge to enable them to debate a subject. The third thing is that debate brings about a level of competition – some children will love the competition and others will not. Weigh it up and give it a go!
There are a number of different ways to set up a debate and it would be wise to investigate these before you begin. Many debates are set up so there are 2 opposing teams of four speakers. The rest of the class would act as the audience. There is also a chairperson whose role would be to introduce each speaker and organize the floor debate. A time keeper would also be a good role to ensure people stick to time.
Why not show a video clip of a debate before you start so the children have a clear idea of what this should look like.