Are you trying to get the audience members to pay attention and have interest in what you have to say? There are several different audience participation activities that you could use. Asking questions, requesting volunteers, or a quick creative activity, are all good techniques to consider.

Ideally, the method of audience participation that you choose should relate to the audience and speaking topic. Factor this in while making a poster presentation for audience members of varying demographics.

Also consider the space and equipment you have to work with. If you know that their will not be enough of either, make the activity simple. The point is to get the audience involved.