I am currently subbing for a teacher but am covering a class for another absent teacher. So, this class has a test tomorrow. Today, they are taking a practice test. Well, one student is going to be out tomorrow, and in the plan the teacher left, this said student is to take the actual test today. Well, I give the student the test. Another student, who is taking the test tomorrow, goes over and sits next to him. I tell the student not taking the test to move away from that student. Afterwards, I noticed that these two kept looking back and forth at each other. Also, I kept seeing the student taking the test look at the test and then look to his side. He probably did this about five times. It was just so suspicious, especially because he would look directly at me after he looked to his side. I want to write this up, but I feel that I might not have enough evidence to do it. Should this be written up? I'm definitely writing a note to the teacher, but I wonder if I should refer it to administration.