The School Bell Reminder is a chrome extension that is able to tell and warn users of the users next period.
NO LONGER WORKS. THIS CHROME APP HAS BEEN DISCONTINUED.
School Assistant (Same functionality)
The School Bell Reminder is a simple google extension the allows users to input school times and subjects and get notified prior the bell notifying the user what they have next(subject). The extension so is based on 6 day rotation system with 1-7 periods and weekday bell time area inputs. If your school is runs differently please notify me in the comments of http://schoolbellreminder.net63.net/coming-up-school-bell-reminder/ as then i can make adjustments in upcoming updates.