As the name suggests, the group choice activity provides an easy way of enabling participants to choose which group (or groups) they want to be in. After making their choice, participants are automatically added to their chosen groups.
Group choice is similar to the choice activity and has lots of settings in common, such as whether to allow participants to change their choice and whether to limit the number of participants who can select each choice option.
Group choice can be used in a variety of situations, such as allowing students to choose which of their fellow course participants they'd like to work together with, or which project they'd like to work on. We've even made use of group choice in our August 2016 Learn Moodle MOOC, asking participants whether their data can be used to create an open data set for use in research, and adding them to groups accordingly.
Group choice is great for giving power to course participants, rather than having the teacher deciding group membership, or membership being determined randomly or alphabetically.