As the teacher, create a list of possible topics for debate. Ask each student to submit a piece of paper indicating three topics from the list that he would like to debate, in order of preference. After reviewing the responses, assign topics to students. Debates can be individual with one person supporting the issue and one opposing it, or team-based with two students working together as a team on each side. After selecting the topic for each student or team, assign each student or team the supporting or opposing side of the issue.
Give students or teams an equal amount of time to present their sides of the issue. After each side has presented its argument, give each a shorter period of time to refute and respond to the information provided by the opposition.
After each side has presented its argument and had an opportunity to respond to the information presented by the other side, allow students that did not participate to ask questions. Divide the questions equally, with the same number of questions being asked of each side. This will teach students to speak about the subject without having a prepared speech for this portion.
Determine how the winner of each debate will be chosen. Let everyone in the class that is not involved have a vote, or else select a small group to deliberate together and choose the winner of each debate. Set guidelines in advance for determining the winner. Guidelines should award a predetermined number of points to the side that provided the most information, responded to the other side most effectively and most successfully answered questions from the audience. Dividing scoring into those categories can focus the scoring on the debate instead of making it a popularity contest.