I posted about this in the News & Updates section, but I wanted to give this forum a heads up too, since this has been one of our biggest requests from teachers for a while now.

Teachers and coaches can now add personal "nicknames" (display names) for students that they coach!  Teachers had reported difficulty keeping track of their students’ identities based on their usernames alone, so we added this feature so that teachers can now manage their classes using any names that they want for students.  

 We'd love to hear any feedback you have.

 To add or change a nickname, go to Manage Students and click "Edit Display Names." Please note thatdisplay names are only visible to you; students will continue to see their username when they use their own accounts.  This is in order to protect the student's privacy and to avoid impacting their account login information.  

Once you add a display name to a student, that name will be visible throughout your coach reports, including any data exports.

For additional reference, here is the FAQ (with larger screenshots) on the feature.