When children are set the task of presenting to the class it is useful to give some guidelines. Examples could be:
Children may find it helpful to try to model the format on factual TV programmes they have seen.
It is helpful to agree success criteria with the class for the presentation ("Groups must include 5 facts about.... ").
After each presentation ask the class to provide feedback to the presenting group. This needs to be done in a supportive learning environment. Ask children to say one good thing about the presentation and one way that it could be improved – encourage children to match their feedback to the success criteria that you have agreed.