In collaboration, two or more individuals are working together to solve a problem. They have to coordinate their activities to yield a successful result (Dillenbourg, P., Baker, M., Blaye, A., & O'Malley, C., 1996; Slavin; Johnson & Johnson).
Some authors distinguish between 'cooperation' as work that "is accomplished by the division of labor among participants" and 'collaboration' that involves "mutual engagement of participants in a coordinated effort to solve the problem together" (Roschelle, J., & Teasley, S., 1995). However, also in collaboration, task distribution can occur; but in contrast to cooperation, the subtasks are not independent, and coordination is needed to finally solve the problem (Dillenbourg et al, 1996).
Different strategies for supporting collaborative learning include collaborative observing (see the Craig et al. study), scripted collaboration (see the Rummel et al. study), and peer tutoring (see the Walker et al. study).
When this variable is manipulated in a study, then it is usually a contrast between solo work and collaborative (pair) work. Some studies also vary the type of scripting or collaboration scaffolding.