LOL!
When it came to illnesses, I let them do what they wanted that last day, as long as it was RESTFUL. The could read, play games, sleep, watch TV or whatever. They could NOT run, go outside, play rough or do any chores. They liked that day!
We got to lie on the sofabed in the living room and watch games shows when we were sick.
Unless the child is desperately ill, he gets bored lying in bed fairly soon. When they’re well enough to get out of bed, they’re well enough to do a math worksheet or write a paragraph!