As a teacher, you can select multiple assignments in your class and download a CSV file of overall grades for all the students in that class.
Downloading Grades for an Assignment
Login to your Teacher account.
Select the desired Class, then select the 'Assignments' tab.
To download grades for a single assignment, click on the download icon on the right.
A CSV file will be automatically downloaded onto your device.
Downloading Grades for Multiple Assignments
To download grades for multiple assignments at once, select all the desired assignments and click 'Download Grades'.