Informative Speech

The whole point of giving an informative speech is to leave your audience with a feeling that they have learnt something. If you tell people what they already know you wont keep their attention for very long.
Putting together an informative speech doesnt necessarily mean that the speaked has something new to say. It can mean that the information is presented in a way that enables the audience to fully understand the meaning of concepts for the first time.

When preparing your outline you need to ask yourself, "what does my aidiance already know about this subject?" For example, if you are speaking to a group of third year computer science students about software you would not repeat basics that they already know.