Motivaton is always an issue, even without the distance portion of learning. Teaching on Zoom to 30 blank boxes where they wouldn't turn on their microphone or camera was difficult. I encountered the same problem as you and asked my department for some guidance. Several ideas that were given to me:
- Have a theme every day/week to increase participation. (crazy hat and hair day were popular!)
- Shorten assignments to what you really want to assess. Students were far more willing to answer 5 questions as opposed to 10-20.
- Have students own their learning by using inquiry-based projects or project-based learning.
Good luck! Hope these help if we go back to distance learning in the fall.