Help the child prepare a handout that outlines key elements of giving any presentation or demonstration to an audience. The level of complexity they choose to provide in their handout should be based on the age of the presenter and the audience.
Use the Socratic method to assist your students in understanding how to delve deeper into a subject. This will translate into better analytical skills and thus help them to be better presenters when asked questions by an audience at the end or a presentation or demonstration. The Socratic method consists of a back-and-forth question and answer exchange between a teacher and his students that is designed to flesh out the issue.
Provide a student with a range of options that can be used to assist him during his demonstration. For example, there are several types of supplemental materials that can be handed out or used to assist him in demonstrating his project or explaining his topic to his audience. These include overhead transparencies and posters.