Frequently, I like students to work in partners but I found that the same students were working together all the time and some of the kids were too shy to pick a partner or never selected by others. Now I make a 'Group Chart' at the beginning of each marking period. The chart has the students' names across the top and down the side. Whenever two kids work together, they put the date in the box where their names intersect. This allows the same pairings only twice and working alone only once. Now when I tell them to pick a partner, the more aggressive and confident students reach out to those who aren't because they know they have to work with everyone in the class at some point. Even the shy ones use this as a license to approach those they normally would not.