Schedules move most in the first three weeks of a term. A section outgrows its room after add/drop, a lab moves to another building, an instructor is replaced. Later come the one-off changes: an instructor is sick, a snowstorm closes campus, a make-up class is added on a Friday. Each change takes a minute to enter in the SIS. The real question is how long it takes to reach students.
Usually the answer is: whenever they read the message. A notice goes out through the SIS portal or by email, while the calendar on the student's phone still shows the old room. Ten minutes before class, students check their calendar, not their inbox.
Why do schedule changes reach students so slowly?
Four things slow a change down between the SIS and the student.
- Copies. Every calendar entry that isn't connected to the SIS is a snapshot: typed by hand, captured in a screenshot, imported once from a file. Snapshots don't change.
- Refresh cycles. Subscribed ICS calendars are refreshed by the calendar app on its own schedule. Outlook and Google Calendar decide when to fetch the feed again, which can take hours and sometimes longer. The institution can't force it.
- Targeting. A room change affects one section; a cancellation affects one occurrence of one section. Messaging tools broadcast to lists, and people who are rarely affected learn to ignore them.
- Duplicates. A sync that deletes and recreates events instead of updating them leaves duplicates and lost reminders whenever something fails halfway, and teaches users not to trust what they see.
What does a late update cost?
For students, it costs a walk to the wrong building, or a commute for a class that was canceled at 7 a.m. Students who work, commute from far away or arrange childcare around their timetable pay the most.
For instructors, it costs the first ten minutes of class while people find the new room, and the same announcement repeated in class, by email and in the LMS.
For staff, it costs time at the registrar's office, the department office and the IT help desk, answering the same question for every student who didn't see the notice.
And it costs trust. After a calendar has been wrong twice, students stop relying on it and go back to checking the portal every morning. That undoes the reason for putting schedules in calendars in the first place.
What doesn't work
An email or portal notice on its own. It is necessary, and for last-minute changes it is the only thing fast enough to reach people on their way. But it doesn't change the calendar, so the wrong information stays in front of students for the rest of the term.
Asking students to update their own calendars. Many won't. Those who do may fix one occurrence and break the series, or fix the series and lose the exceptions.
Republishing the ICS feed. The feed itself is updated immediately, but subscribers only see the change at the next refresh of their calendar app. The comparison of ICS feeds and real calendar sync explains why that delay can't be configured away.
Deleting and recreating everything every night. It looks simple. In practice changes arrive once a day, students may receive cancellation notices for classes that aren't canceled, depending on how the events were created, and anything they added to an event disappears.
Manual fixes by IT. For two sections, fine. For a campus closure that touches hundreds of sections, not in the time available.
How to fix it: one rule per type of change
Start by listing the changes your institution actually makes and what each one should do to the calendar. Most fall into eight cases.
| Change in the SIS | What should happen in the calendar | Who sees it |
|---|---|---|
| Room change | The location is updated on the existing event | Students and instructors in the section |
| Time change for one session | That occurrence moves; the rest of the series stays | Students and instructors in the section |
| Session canceled | That occurrence is canceled or marked canceled | Students and instructors in the section |
| Make-up session | A one-off event is added outside the series | Students and instructors in the section |
| In person to online | The room is replaced by the Teams link and the mode changes | Students and instructors in the section |
| Instructor replaced | The events move from one instructor's calendar to the other's | The two instructors |
| Student changes section | The old section's events go, the new section's arrive | That student |
| Campus closure | Every session that day is canceled | Everyone with class that day |
Then build the process around six rules.
1. Enter changes in one place only
The SIS is the source of truth. If a department edits a calendar directly, the next sync either overwrites the edit or contradicts it. Every change goes into the SIS first; the calendars follow.
2. Sync the differences, not the whole schedule
Compare the current SIS schedule with the last version sent and push only what changed. That keeps updates fast, keeps API calls low during the busy first weeks and makes every change traceable.
3. Update the event people already have
Each class meeting carries a stable ID, so a room change patches the location of the existing event. The student keeps the same event, in the same place in their calendar, with the reminders they set.
4. Pick one cancellation convention
Two approaches are defensible: remove the canceled occurrence, or keep it with "Canceled" at the start of the title. Keeping it tells students the class was canceled on purpose rather than lost by a sync error; removing it keeps the calendar clean. Pick one and apply it institution-wide.
5. Be clear about timing
A native sync can bring a change to calendars within minutes. A change made at 7:45 a.m. for an 8 a.m. class still needs a direct message. Publish the rule so that faculty and staff know which channel to use when.
6. Keep a log
Record what changed, when, and when it reached each calendar. When a student says they were never told, the log answers the question. Audit trails also help institutions document how personal information is handled, which privacy laws such as Quebec's Law 25 emphasize; confirm the specific obligations with your privacy officer.
How Calendo handles it
After the first push of the term, Calendo's main job is change propagation. When a room, a time or a teaching mode changes in the SIS, or a session is canceled, the change is reflected in Outlook, the Teams calendar, Google Calendar and the Moodle and Blackboard calendars within minutes.
Because Calendo writes native events through each platform's API, the change lands on the event the student already has. Nobody re-subscribes, nobody deletes a duplicate, and the room shown ten minutes before class is the room in the SIS. Online sessions carry their Teams meeting link, so a switch from in person to online changes what students click, not just what they read.
Students who subscribe through Calendo's ICS feed, for Apple Calendar for example, receive the same change at their app's next refresh; native calendars are the fast path. Every action is logged. The data flow from each SIS is described on the SIS integration page, and the Teams side on the Microsoft Teams calendar sync page.
For how the timetable gets into calendars in the first place, see how to sync class schedules to Outlook, Teams and Google Calendar. For courses that mix formats, see in-person, online or hybrid: the right room or Teams link in every event.
Key takeaways
- Schedule changes reach students slowly because their calendars hold hand-made snapshots or ICS subscriptions refreshed on the app's schedule.
- Each type of change, from a room move to a section switch, needs a clear rule for what happens to the calendar event.
- Updating the existing event by a stable ID beats deleting and recreating events, which causes duplicates and lost reminders.
- Native calendar sync can carry a change within minutes, but same-day changes still deserve a direct message.
Watch a room change reach every calendar
A 30-minute demo where a schedule change entered in the SIS appears in Outlook, Teams and Google Calendar within minutes.
Book a demoFrequently asked questions
How fast can a room change reach students' calendars?
With native calendar sync, which updates events through the Outlook, Google Calendar or LMS APIs, a room change entered in the SIS can reach calendars within minutes. With an ICS subscription, the timing depends on when each student's calendar app refreshes the feed, which can take hours. With hand-made copies, the change never arrives unless the student edits the event.
Should a canceled class be deleted from the calendar or marked as canceled?
Both are defensible. Removing the occurrence keeps the calendar clean; keeping it with "Canceled" at the start of the title shows students the class was canceled on purpose rather than lost by an error. What matters is to cancel only that occurrence, never the whole series, and to apply the same convention across the institution.
Do students get notified when a class changes room?
Don't count on the calendar for that. Depending on how events are written, an update may or may not trigger a notification, and many students ignore notifications anyway. What the sync guarantees is that the room they check before class is the right one. Urgent, same-day changes still deserve a direct message through the SIS portal, Teams or email.
What happens to a student's calendar after they change sections?
With a sync driven by the SIS, the next run removes the old section's events from the student's calendar and adds the new section's, with the new rooms, times and meeting link. The student doesn't have to delete anything. With an ICS feed, the same change waits for the next refresh; with hand-made copies, the student has to redo every entry.