You seem to be running Moodle 3.11 or higher, based on links in the Brandeis LATTE documentation to the Moodle documentation. If you edit the Course settings and expand the "Course format" section, you can see the available course formats in the "Format" drop-down menu, and you might have flexible sections already available.
Moodle in English -> Assignment How to move assignments to a folder -> Re: How to move assignments to a folder
by Eoin Campbell -