I will also roam during a test; however I noticed that there was strong similarities between certain peoples tests resulting in a few grade point averages making a remarkable improvement. I found a way to locate the cheaters from the workers.
I generated 5 copies of a test that had mostly math questions on them. Though the questions looked identical, some of the values were different so that the final answer would be different. It was amazing to see the answers that matched the students that had good grades.
When reviewing the test with the class after they had been graded we went through setting up the formula and general solution to the point of substituting values which was when I let them work the remainder themselves with a suggestion if their was a disagreement with their grade to see me after class. When one of the students complained that his answer was correct we completed the problem on the board which naturally resulted in a different answer than he got on the test. It was about that time I let it slip that there was multiple versions of the test out there. There were a few red faces, no one was directly accused and cheating has been greatly reduced. They know that I know there was cheating and now they are not to sure if it is safe to cheat.
