Giving informative speeches can be fun, but it can also be quite difficult to do well. If the audience already knows a lot about the topic, then you risk boring your audience members. If the audience doesn't know a thing about the topic, the risk is presenting information that is so over their heads that they stop listening.

For those two factors alone, my first tip to keep the audience engaged while also informing them is to know and understand who your audience is. You have to know what they do know and don't​ know. This allows you to craft a speech that makes use of the audience's base knowledge. If your new information uses existing knowledge, the audience is kept engaged longer because they are feeling grounded in existing knowledge while expanding it with new information.

My second tip is to use anecdotes. When a speaker gives information and uses a concrete example through story to help further explain, the audience is generally engaged because human beings love stories. A key is that the story has to help develop the information being given in the speech. It can't be a random story, otherwise you risk the audience remembering the story and not the informative parts of the speech. An effective story that incorporated the information can actually more deeply set the information in the minds of the audience.

My third tip is to use visual aids. Effective usage of visual aids is automatically engaging to audiences because it gives them visual variety. They don't always have to look at you. Additionally, a visual aid can be extremely helpful in an explanation. A line graph showing financial growth conveys the information far better than just your voice. A model of DNA helps audiences understand the general shape and structure of a molecule that in other situations would have to be completely imagined.