Contestant draws three topics from a box and selects only one. Contestant has 2 minutes to prepare a 5 minute speech on the selected topic (with a 30 second grace period).
Note cards may not be used during the speech.
See this link for a list of possible topics. There are many others online. Be aware that famous quotes are often used as topics.
Impromptu is perhaps one of the most enjoyable events. Although it appears that no prior preparation is necessary, those contestants who do well in impromptu usually do much advance preparation. There are many links online that will help you with this event.