As a jury of a debate, I would like to consider several issues as the judging criteria for the debate on Monday.
First of all, the basic points for pro team and con team must be explicit and reasonable. In their first round, they must build at least one solid point of view, which should be prepared well before the debate. What I expect to hear about is the real voice for the citizens that which one is more important, privacy or security, and why. The best form of their speaking is the combination of points and examples in order to make the point more convincing.
Secondly, after hearing the point of the opposite team, they should know what is the core statement of the opponent and build up an effective counterpoint for that. For example, if the pro team states that electronic surveillance could help track criminals, I expect the con team to consider that sometimes it does not work with the system and there might be false positives that lead to the wrong direction and harm innocent people.
Thirdly, they should also learn about the possible weakness of their own points. If they could point out the weakness by themselves and do concession. Then they actually effectively eliminate one possible point of opponents. Both teams should prepare these ideas well before the debate so that they could react quickly in the class.
People cannot convince others thoroughly, but they could use their ideas to influence others' thoughts, at least make others agree to part of their points and consider the issue from some new aspects. If they made it in this level, then they might do better than the opposite side and win the debate.