A) let them decide if PJs can be worn....maybe a yes, if they will do their homework, most likely they'll be sent home with some.
B) Allow for playtime if basic chores you agree on are done.
C) Here is the scary part, most likely if a school is canceled so will be all of their organized sports and groups. That means you'll be together a lot! So, yes, you may want to permit a bit of screen time. Maybe even join them in a shared game.
D. Try out an actual schedule, 9:00 to 9:30 reading, then 9:30-10:00 maybe math. At least we can look at this as a time to know what your kid is actually studying.
E) Try the history channel or other documentaries on Netflix.
F) Or how about watching and discussing Ted Talks. Here is a great list of 17 that are great starters for kids.
G) "Finish other homework if it’s been assigned. If not, science videos. On the first day, our only job is to watch two minutes worth from these six different science video channels":
minutephysics
MinuteEarth
TheBackyardScientist
The Brain Scoop
SciShow
Veritasium
These are just a few ideas, let me know if you have more, Juli