Most students care a lot about doing well on assigned speeches.
Obviously the grade is a primary motivator for some students, but for others, just looking good in front of their peers is actually more important than the grade. In order for students to stand a chance of doing well on an assigned speech, they should know that the normal amount of preparation time is about one hour per minute. That means that a speaker should spend about three hours composing, revising, and practicing a three-minute speech. Most students have no idea that they need to spend that much time, and often their early efforts show that they did not spend enough time working on their speeches.