The most effective system that I ever used was called the "stoplight" management system. You can download a free set of directions and a picture of the stoplight bulletin board by clicking this image.
To use this system, I created a "Go for Green" bulletin board in my classroom. I posted a large illustration of a stoplight, but mine had a slight modification. It had four colors: green, yellow, orange, and red. I arranged a set of library pockets around the stoplight, and each numbered pocket represented a student in the class. Everyone started off each day on green. The first time a student engaged in an off-task behaviors, I pulled a yellow tag from the pocket at the base of the stoplight and inserted in the student's pocket on top of the green tag. This was simply a warning. If the off-task behavior continued, I added an orange tag to the student's pocket and they had to complete a Time Out form. Red was reserved for severe infractions and resulted in a trip to the office and/or an immediate call to parents.
Go For Green Stoplight System
I wanted to share the entire system with you and make it easy to implement, so I began to write out step-by-step directions. The next thing I knew, I was creating a pattern for the stoplight, adding a class chart, including two Time Out forms, and more! What started out as a simple write-up morphed into an entire Mini Pack! The Go for Green Stoplight Management packet also includes a copy of the teaching and learning poster above. You can preview the whole thing online here or on TeachersPayTeachers to see if it meets your needs. If you would like to purchase the complete packet shown here, you can download it from my TeachersPayTeachers store. I hope you find this system to be every bit as useful as I did!