I haven't read the other posts and need to get my own kids back to the table lol but I wanted to chime in....IT"S A SICK DAY!!!!!!!
"They" say a kid needs something like a month decompression time for every year in public school. Some take several months. For now I would only do "fun" stuff like science, history, art, music - whatever floats your sons boat. Then add 1 subject at a time. I would just plan some fun museum trips, trips to the zoo, playdates w/ other HSers this week.
Give him a few days to recover from being sick. SNuggle up on the couch w/ a good NOVA science show - always works for us!
