This spring (2020) MIT moved all its classes online because of the COVID-19 pandemic. It made available licenses for various nonfree programs, but I objected to them on grounds of principle. For my class, an advanced class in computer programming, I made arrangements to avoid suggesting any nonfree software to my students.
Instead, I used an installation of BigBlueButton running on a server owned by the Free Software Foundation. Rubén Rodriguez of the FSF helped get this and other software working. (Thank you, FSF and Rubén!)
The class used a draft textbook that Chris Hanson and I have written. The book is entitled “Software Design for Flexibility (how to avoid programming yourself into a corner)”; it will be published by MIT Press soon, with a Creative Commons Share Alike license (and all the code in support of the book is under the GNU GPL).
I also did not ask my students to use nonfree software for one-on-one conversations about classwork, or thesis work, or projects. I used a Jitsi Meet server that I installed on an obsolete and otherwise useless computer that was sitting idle in my laboratory, on its way to the electronics junk heap.