When I noticed someone being an awesome friend, I gave them one of these cards to take home. I would call them up in front of everyone at the end of class, and make a big deal of them being a fabulous friend. They were so proud to show this to their parents!
Lastly, give students time to get to know each other in a relaxed atmosphere, not always structured lessons. Students need time to get to know each other and build those relationships. I was fortunate to have 20 minutes of “free play” at the end of every day for students to work on social skills and use their imagination through play. I would play games with my students during this time and observe how they interact with each other. It’s another way to model team building skills and provides an opportunity for you to get to know your students better as well. Sometimes we have too much pressure to fit in all the academics, that we lose that valuable time of just getting to know our students.