Student learning groups can help ensure participation of all students. They should bre formed with first thought to diversity of backgrounds, skills, and experience. One advantage of student learning groups is that students can bounce ideas off of one another and get a reaction of rememdiation before sharing with the larger group, and that more advanced students can mentor those who are struggling.
Learning groups can be formal, such as those pre-determined for projects, or informal and organized on the spot for activities such as discussions. You should ensure the product, work allocation, and grading for group projects is structured and pre-determined.
