Classroomscreen is an amazing online tool that allows you to "display the instructions for your lesson in a clear and visual way. Choose from over 13 widgets to support your class activities and help students get to work."
A new tool available to you is Group Maker (you can make 3 lists for free). Each list has the ability to have up to 100 names.
When you select Group Maker and choose your list you can then adjust how many groups or how many students in each group.
Once your groups are created you have the option to move student names from one group to another as well as the ability to create exclusions in which certain students will not be grouped with other ones.
Embedded below is a 2 minute and 12 second YouTube tutorial.