Informative speaking generally centers on talking about people, events, processes, places, or things. Informing an audience about one of these subjects without being persuasive is often a difficult task to complete. For example, a speech informing an audience about growing peace lilies as houseplants might ultimately persuade the audience to buy and grow peace lilies. All speech has an effect that might enable individuals to self-persuade themselves. The line walked during an informative speech, as opposed to a persuasive speech, is to not make persuasion an explicit and obvious goal. An informative speech on peace lilies might cover both the advantages and disadvantages of these houseplants; a persuasive speech would take a firm position on the virtues of peace lilies.
Tips for informative speaking:
Analyze the audience. What can the audience be reasonably expected to know? If talking to a field of medical professional about cloning, they likely know the basics of DNA. An audience of lay people might not be so fluent in the language of biomedical engineering, and so basic concepts like this will have to be explained. Never presume that an audience has a thorough background in the subject.
Use appropriate language. What are the norms for speaking style for the audience? If they expect lots of jargon and specialized language, the speech should be peppered with such language or else the audience will feel like they are being talked down to. If the audience is unfamiliar with these technical terms, avoid using them or introduce them with an explanation of what they mean.
Explain the importance of the topic. Why should the audience listen? Will this information improve their lives in some meaningful way? Especially with a captive--involuntary--audience, a speaker must establish a connection between their topic and the interests of the audience.
Express interest in the subject material. Why should an audience listen if the speaker seems just as bored as they do? A speaker who confesses their own interest in the topic might activate the audience to share a similar interest.
Show, don't tell. Don't most people learn through doing or seeing? Being told about a process, like cloning, could be informative, but probably not have as great an impact as being shown the process with pictures or perhaps even lab equipment. Informative speeches often benefit from a demonstration or visual aid. Technology can assist "showing" when the subject is not easily brought physically into the room (imagine the troubles of an informative speech on the sun if a prop was required!)
Be specific. Informative speeches thrive on detail, and dive on generalities. If speaking about basket weaving, carefully note what types of weaving materials work and do not work for basket making. Audiences are often impressed by detail, but be careful not to become so detail-oriented that the big picture of the speech is lost (missing the forest for the trees).