Well, if you have a HyFlex class, you can simply require all your students to meet online for that session. This works well if they all have network access, the tools and ability to participate in the online mode, and the time to do so. In our graduate program, it’s never been a problem.
We had occasion to do this on a recent night of classes after our university lost most electric power for several hours. An hour before our graduate courses were scheduled to begin for that evening, all classes were canceled. Because I am using the HyFlex design in the courses I teach, all I had to do was send an email to my students telling them to complete their participation requirements online (and asynchronous) for that week. Because the online option was already prepared for those students who were going to choose to participate that way already, I didn’t have to create a single new resource or activity … the online course materials and activities were already there!
I’m sure being forced into the online mode was not convenient or simple for some students, but it was better than missing out on up to 10% of the content of their course. (Graduate students, perhaps more than many undergraduates, often want to get as much as possible from their course experiences, since they are often paying dearly, in time and other resources.)
There was still some difficulty, since while the campus power was off our locally-hosted LMS (ilearn) was off line, so students couldn’t immediately access course materials during the regularly scheduled class time. With a little schedule accommodation for quizzes and such all were able to complete the participation requirements later during the week.
It’s nice when things work out well, even when unplanned events drive a change in plans. And in our geography (San Francisco Bay Area), being able to recover quickly from an unplanned event (such as a major earthquake) that could close our campus for days or weeks is very important.
Note: Over the past few years (2010-2018), we’ve had unplanned campus closures for: rain/windstorms, hazardous materials in a large teaching building, extended power outages, excessive atmospheric smoke (more than once), and transportation strikes. With HyFlex courses, the administrative question comes up – if the campus is closed, are faculty allowed to teach online as an alternative? The answer to this question is more political than practical, and will need to be answered for each campus using HyFlex.