Pair programming involves one student, the "driver," using the keyboard and mouse while the other student, the "navigator," provides directions and support. Pair programming is used in industry because it helps programmers learn from each other and write code with fewer bugs. It is also helpful for demonstrating that programming is a collaborative activity.
Have older students watch the NC State video: www.tinyurl.com/PairProgrammingVideo
Have younger students watch the Code.org video: https://www.youtube.com/watch?v=vgkahOzFH2Q
See this and related tips as a Tip Sheet: http://csteachingtips.org/tips-for-pair-programming