Key considerations

This page list some common misunderstandings and edge cases that you might want to consider in designing and implementing your Classroom add-on. You're encouraged to implement failsafes and tests that cover these cases.

Classroom concepts

This section highlights edge cases and concepts that apply to all of Classroom.


A course is the central organizational unit that connects teachers to students. The following apply to all courses within Google Classroom.

Regarding teachers of courses:

  • A course may have more than one teacher.
  • Teachers may be added to a course at any time.
  • Teachers may be removed from a course at any time.


An assignment or post is any posted content or task that's communicated to students.

Regarding assignments:

  • An assignment may be assigned to a subset of the students in the course.
  • An assignment may be graded or ungraded. Teachers may change the grading status of an assignment at any time.
  • An assignment may have more than one attachment.
  • An assignment may have attachments of different types. For example, one assignment might have Google Docs, YouTube videos, and add-on attachments simultaneously.

Copied assignments

Teachers may copy an assignment by copying a course, reusing an assignment, or publishing an assignment to multiple courses. Read our page on copied content to understand how the add-on can handle these scenarios.