Overview
The main goals for an informative speech are to help explain a specific subject and to help the audience remember the knowledge later. To achieve these goals, a speaker should consider how best to package the complex understanding that they have cultivated of the topic, from personal experience and research, into an easily communicable form for the audience.
Complexity
One way to deliver an effective informative speech and ensure that the audience leaves your speech informed is to tailor the complexity of the speech to the specific audience.
An audience listens to a speech at a conference
Tailor the complexity of your speech to the specific audience you will be delivering it to.
Never presume that your audience has a lot of background knowledge on your subject, but also don't assume they know nothing. The audience is an integral part of public speaking; not only will they hear your speech, but they should be an important component that informs the writing of the speech as well. Consider, for example, if you are preparing to deliver an informative speech on the topic of cloning to an audience of geneticists. Their professional training will have given them an extensive understanding of DNA. Because of this, you would want to tailor the complexity of the speech to match the knowledge that the audience already possesses, meaning that the speech could contain lots of technical terms with little explanation because the audience will already understand what those terms mean.
Conversely, consider delivering a speech on the same topic to an audience of college students. This audience, even if they have taken biology classes, will not possess the same expertise knowledge that professionals do. Therefore, you would want to tailor the complexity of your speech to the knowledge of the students, using fewer technical terms and more general explanations.