Instead of having class rules, I had class jobs. On the first day of school, I always told my group of second graders that they were so smart and responsible that they were ready for jobs instead of rules. We discussed how our classroom was a team/family, and we all worked together to make sure our classroom was a great place to be. Then, after a discussion about jobs and what happens if you don't do your job, I let my students come up with a list of their jobs and my jobs.
They shared their ideas while I kept track of them on the board. Then, after school I made a poster of our jobs and had it up the next morning. Whenever I caught a child not doing their job, I just simply asked them, "Are you doing your job?", and that would usually keep them on track. If not, I had the card system in place.
I apologize for the not-so-great photo. I just came to realize I never took an actual photo of my job chart. In this particular poster, I just created a chart showing our jobs, but I have also created Venn Diagrams in the past since several jobs overlap, and it's another great way to remind students of how to use a Venn Diagram.
I always loved this system because it really gives students the feeling of responsibility and that their classroom truly is their classroom. Plus, they're smart kids, and they come up with every rule and more a teacher could ever think of. Ha!