Alerts you when class is about to end. Data can be sourced from a spreadsheet or a Google Calendar. You can specify the number of minutes before the end of class that you wish to receive a notification. You might use this to remember to set your class a reflection or exit ticket.
Note about permissions: The Spreadsheet permission is required in order to get programmatic access to a Google Sheet (even if it’s a public sheet). Calendars permission is to access your calendar. If you are concerned about these you are welcome to review the source code at https://github.com/askvictor/timetable-alert and/or install the extension from source.