Informative speech: what topics not to use
Writing and delivering an informative speech can be one of the most enjoyable assignments a student in a writing or communications class receives. Most instructors allow students to choose their own topics for an informative speech, and it can be a very pleasant experience to choose to share your knowledge about a topic you've a passion for. However, it's important to choose the right type of topic. To do so, be sure to avoid these common mistakes:
Of course, it's difficult to avoid expressing your opinion altogether. After all, you've chosen the topic primarily because, in your opinion, it's interesting. Keep in mind that you aren't making a case for that, however. You're simply teaching about it, not advocating for it. On the same note, you'll want to avoid deeply personal topics.
Extremely controversial topics
In theory, avoiding opinion based topics makes avoiding controversial topics easy—in practice, it's somewhat harder. You may not thing that your beliefs about politics or evolution are biased, and you may be entirely committed to presenting an unbiased perspective. Nonetheless, it's far better to avoid these topics entirely. However well-supported and factual you may believe your speech to be, there's a reason these types of topics are hot-button issues. For that same reason, they make poor choices for informative topic selection.
Topics which are too narrow
The issue with narrow, specialized topics is that your audience may not have the necessary background knowledge to fully appreciate what you're speaking about. To determine whether or not a topic is too narrow, you'll need to consider the target audience. At a convention for comic book lovers, an in-depth discussion of a minor character that appears in only one or two publications may be well received. For a more general audience, which may lack an understanding of the universe the character lives in, the other characters with which he or she interacts, etc., the topic is far too narrow.
Topics which are too broad
Again, this is largely based on your target audience. If the audience already has a broad knowledge of the topic and your speech adds nothing to that knowledge—fails to “inform” them of anything new, it comes across as lazy at best, boring at worst. To choose a topic of appropriate scope, take some time to consider the baseline, average audience member's understanding of the subject and work from there.