As a high school Social Studies teacher, I will be asking my students to research. Students must be able to tell fact from fiction; and truth from propaganda. Students must be able to search primary documents and scholarly journals to find how fact and opinion can merge to provide powerful insight. My hope would be that students, by this time, have already been taught that plagiarism is wrong and must be avoided.
Of course, I will have to reinforce that. In any classroom, in any group setting in the world, there will be those present who think they can cheat and get away with it. I must first of all provide the model of proper research. I must be aware of all copyright and fair use policies and give my students a fair and legal teaching experience.
When I hand the ball to them, I must explain how important it is to do their own work; and then explain the consequences for plagiarism. I must make sure each student knows what plagiarism is and what it means. I must use all learning techniques, from written words to video, audio and online tools, to make sure no student is left out of the learning process. This is always true, but vital at this point.
As they work through their research and writing, it is important that I allow them to work with group members, so teams can 'police' each other. I must work with the teams step-by-step to show them how interesting, fun and beneficial proper research can be. I believe if you make them aware of what the consequences are, show them the way to do it right, and connect what they are doing with the real world, this will go a long way to ensuring that a bare minimum of students try to plagiarize someone else's work.