Google Classroom ties Google Drive, Google Docs, Sheets and Slides, and Gmail together to help educational institutions go to a paperless system.[13] Google Calendar was later integrated to help with assignment due dates, field trips, and class speakers.[2] Students can be invited to classrooms through the institution's database, through a private code that can then be added in the student's user interface or automatically imported from a school domain.[14] Each class created with Google Classroom creates a separate folder in the respective user's Google Drive, where the student can submit work to be graded by a teacher.[15]