Classroom weaves together Google Docs, Drive, and Gmail so teachers can create and collect assignments paperlessly. Within Classroom, teachers can create an assignment, use it in multiple classes, and choose how students complete the assignment (for example, whether each student receives an individual copy or all students work in the same copy of the assignment). The teacher can track who has completed the assignment and who hasn't, and provide feedback to individual students.
Here's an example of the assignment flow between a teacher and a student:
Teacher
Teacher creates an assignment with an attached Google Doc.
Teacher grades the assignment.
Student
Student edits the copy of the homework and turns it in.
Student reviews and edits the copy of the homework.
Both the teacher and students can see a list of pending and completed class assignments. The teacher can see the all of the grades for an assignment, and students can see their own grades for completed assignments.