Use a Two-Step process when students first work in pairs - When you initially have students pair off, there is a high potential for students to become disruptive. The more structured the transition, the better the chance it will go quickly and smoothly. Thus, it is useful to break the process into two steps. First, have the students pair off and then, when they are settled, give them directions for how to work with their partners.
Use Simple Methods for Pairing Off - When you first have the students pair off, use simple methods - Pairing students with those they sit next to or across from often works best.
Monitor Students Behavior and Content - When students begin working in pairs, let nothing distract you from monitoring their behavior and narrating or correcting it. Do not take any questions or become involved in any other activity besides making sure the students learn how to successfully work with their partners.
Work the Room - Avoid the temptation to spend too much time helping students, standing at the front of the room, doing paper work, or preparing materials for another activity. When students pick up on the fact that you are not "withit", you know what can happen! While students are paired off, keep moving around the room to monitor and give feedback to the students.