An extemporaneous speech is one prepared quickly, within a half hour or less. Many schools offer extemporaneous speaking competitions. When practiced, writing extemporaneous speeches can improve public speaking skills as well as promote on-the-fly thinking. These speeches are generally not very long although even five minutes can seem a long time when you are speaking. Like all speeches, they are designed to inform, inspire or persuade.
Identify your topic and start brainstorming on topic details. If possible, choose a topic with which you are familiar. If you have thirty minutes, spend the first ten minutes brainstorming to think of everything you can about the subject in that time. For example, if you want to persuade your audience to recycle, write down as many reasons as you can think of to recycle. Jot down quick notes like "reduce pollution," "setting example for future generations," "conserve resources," "conserve land" and "create new jobs." Write everything that comes to mind; you may later decide to delete some ideas.
Outline your speech. Start with the title, then list a few sentences for the introduction. For example, write "This morning I had a soda, and I almost threw away the can. But then I thought I should recycle." Then write what you will be talking about, specifically "Everyone should recycle and today I'm going to tell you why." Use a highlighter to stress your main point, "everyone should recycle."
Create the body of your speech. Limit yourself to the most important points you want to make and be sure they all relate directly to your subject as you do not have time to go off topic. Choose a few notes from your initial list and further clarify them. For example, write a paragraph about conserving land, another about reducing pollution and a third about creating new jobs.
Expand your main points. Take your three or four main topics and list a few examples, quotes or statistics for each section. Provide three pieces of supportive information for each of the three sections that are legitimate and backed by source. For example,"recycling reduces air pollution because the production of glass releases harmful gasses into the environment."
Write your conclusion. Use only about two or thee minutes of your preparation time to do this; conclusions don't need to be long. Restate your main arguments. End with an anecdote, quote or call to action. For example, "I encourage you all to go home tonight and gather up your old bottles to take to the recycling center tomorrow."