In HyFlex classes, students can select their participation mode and flex between modes. They can choose to: 

1. Attend face-to-face synchronous class sessions on campus

2. Attend synchronous class session virtually via video conferencing 

3. In the most flexible models, they can also participate fully asynchronously via recorded lectures, etc

Hyflex classes typically make all learning materials, class sessions, and assessments available through Canvas and all students, regardless of their participation mode, achieve the same learning objectives.

Brian Beatty, Associate Professor of Instructional Technologies at San Francisco University, and editor of  Hybrid-Flexible Course Design (Beatty, ed., 2019) presents four core values informing HyFlex courses:

• Learner Choice — The course provides alternative participation modes that are meaningful and allow students to choose the mode of engagement that works best for them.
• Equivalence — The modes, though not equal, provide equivalent learning outcomes. All students are expected to reflect, contribute developing ideas, and interact with their peers in the process of learning.
• Reusability — Artifacts from learning activities in each mode are captured and can be reused in other modes. Representations of in-class activities (recordings, discussion notes, etc) are available online for all students; activities produced by online students (asynchronous discussions, posted files, etc) connect to and support all students.
• Accessibility — Students are equipped with the technological resources and skills to equally access all participation modes. Universal Design for Learning principles are considered.

To start to consider these values in the context of a HyFlex course or session you would teach, the following worksheets from Beatty’s OER eBook may be useful:

• “Analyze and Confirm or Modify Expected Student Learning Outcomes” (Figure 1.4.2 in Beatty, 2019) can help you define learning objectives that apply to all students, whether they are in-person or online. 
• “Plan Student Learning Activities” (Content and Interaction) (Figure 1.4.3 in Beatty, 2019) can help you start to think about learning activities that would map to those objectives for each group of students.

From Columbia University's Center for Teaching and Learning where integrating online students into in-person courses has been a focus for some time.