The HyFlex model is one that is being considered by schools for this fall semester. In this model, teachers teach simultaneously to students in their classroom and other students connect synchronously to the class. It can be labeled in other ways - hybrid, flex, blended - but all of them provide options for students who can’t come to class for health or logistical reasons. For this fall semester, this can also allow for socially distant classrooms because students can rotate through classroom spaces on alternating days.
At my university, NJIT, one model is called converged learning and offers a third option for students to view a class recording asynchronously later. By reducing the number of in-classroom students, they plan to use large spaces to socially distance students in courses that require face-to-face teaching, such as labs and studio courses. For a science and technology university, using physical spaces is essential for many courses.
Some faculty feel it will be very difficult to engage students in multiple locations. HyFlex also pushes faculty back to the "sage on the stage" lecture format that we have been trying to move away from the past two decades in order to increase engagement. many faculty at all grade levels still do not feel comfortable with the online technology even after the emergency switch over to it this past spring.
As an instructional designer, I feel that you need to design a course as a fully online one and consider the in-person portion (if it does occur this fall) as the enhancement. Don't expect the in-person portion to carry more than half of the teaching and learning.
Some things are better done in the classroom. Lecture probably isn't one of those things. Teachers and designers need to consider the differences based on the course, the space, and the instructor. In a FLEXible course, group might be best in-person or easier with more time put online. You wouldn't want to waste any lab or studio time lecturing.
In "Active Learning in Hybrid and Physically Distanced Classrooms," Derek Bruff, director of the Center for Teaching at Vanderbilt University, posted about using the technology. He suggests that you might forego classroom discussion and have students respond to questions using live polling and web conferencing platforms.
For any of the flex models to work, all the class materials, assignments, group work, and other activities need to be ina a learning-management system so that they can be accessed no matter where they are learning. Bruff thinks it's a misconception that flex courses require two versions of a course for the classroom and for online.
If you want to know more about HyFlex, look into Brian Beatty's open-source book, Hybrid-Flexible Course Design.
Kevin Kelly wrote a guest post, "COVID-19 Planning for Fall 2020: A Closer Look at Hybrid-Flexible Course Design" with examples of how a HyFlex class session might work.