When you use the topical pattern, you are breaking a large idea or category into smaller ideas or subcategories. In short you are finding logical divisions to a whole. While you may break something down into smaller topics that will make two, three, or more main points, people tend to like groups of three. In a speech about the Woodstock Music and Art Fair, for example, you could break the main points down to (1) the musicians who performed, (2) the musicians who declined to perform, and (3) the audience. You could also break it down into three specific performances—(1) Santana, (2) The Grateful Dead, and (3) Creedence Clearwater Revival—or three genres of music—(1) folk, (2) funk, and (3) rock.
The topical pattern breaks a topic down into logical divisions but doesn’t necessarily offer any guidance in ordering them. To help determine the order of topical main points, you may consider the primacy or recency effect. You prime an engine before you attempt to start it and prime a surface before you paint it. The primacy effect is similar in that you present your best information first in order to make a positive impression and engage your audience early in your speech. The recency effect is based on the idea that an audience will best remember the information they heard most recently. Therefore you would include your best information last in your speech to leave a strong final impression. Both primacy and recency can be effective. Consider your topic and your audience to help determine which would work best for your speech.