Hi Savitri, Two things. One they can come into a class already formed into a learning group and be ready to learn. They know each other well enough that they know who can do what when working together. The other side is when they come in and are a challenge to work with since they have history and inside jokes, and stories. This type of cohort group can be tough to break into . I give them a chance to work on a project together and see how they function. If they do not get the work done I break the group up and reformat the groups into my groups. This way each group is new and has no history. This format eliminates the majority of the cohort problems and my students are ready to learn. Gary