Students need to not only learn what good character traits are, but they need to have "refreshers" now and again.
When it comes to differentiating instruction, you should find yourself using different materials and offering different questions to students. Students do notice these differences and instinctively feel they are being treated "unfairly." This lesson is the solution to that problem.
By working individually, in small groups, and having whole group discussions, students will work with scenarios in which they must determine if they are "fair", "equal", or "neither." Students will also have practice in looking at situations from multiple perspectives. After this lesson occurs, students should be able to answer any internal questions that may arise when/if they see things that are "different" occurring in your/their classroom.