According to your textbook, The Norton Field Guide to Speaking, the purpose of an informative speech is to "provide new information, explain complex concepts and processes, and/or clarify and correct misunderstood information...by instructing, defining, enlightening, describing, reminding, and demonstrating." Though your words may persuade listeners to try a new hobby or respect an new idea, keep in mind that an informative speech is a factual speech, not opinion-based.
Some common types/topics of informative speeches are:
For more detailed information, search for a whole book on your topic, or even a just a chapter in a book.