Teachers can add their students' sandbox programs to any of their playlists. This lets you assign student created exercises to other students in your classes.
Note: this is only available to teachers with Pro sections. To do so, navigate to your sandbox page and choose one of your Class Sandboxes.
Click on the + button to show a list of your playlists that you can add the sandbox program to.
Once you choose a playlist, you will be redirected to a page where the sandbox program is now an exercise.