In order to create different groupings for classroom activities, projects, and assignments, I like to use a fun, engaging, and inclusive system which is an activity altogether non its own!
How this works is that you have a slip of paper for each student and the slips of paper are pre-grouped into certain categories based on a theme. It is up to the students--having been told only how many students there will be to a group--to mingle and to communicate, with the goal of figuring out who they are partnered with and why.
An example would be that the 'partner picking slips' are arranged in groups of two, each pair being a famous duo. The student who has 'Barbie' would need to figure out that he/she should be with 'Ken'. The student with 'Hansel' would need to find 'Gretel', etc.
I have found this to be a great conversation starter and spontaneous learning activity all while grouping students in an inclusive manner for the next perhaps more curricular activity.
If you enjoy this product, feel free to check out my second set of 'Partner Picking Slips'