Right now the only YDS in BC open on Chol Hamoed Succot is BPY. They are planning activities for the children that don't involve writing. Word on the street is that Yavneh will be open next year as well. They should ALL be open.
Principals will claim that halacha forbids writing on Chol Hamoed unless it is truly necessary or it is done "kili'achar yad" (in a backhanded fashion). Some schools in the past have told children to write with their left hands (or right hands if they are lefties) or to write with crayons, or something else that they don't normally use.
Here's the reality though. Instead of writing a few hundred words in school kids will be texting a few thousand words from home, which is arguably just as bad. And the parents will mostly be working, whether it is truly necessary or not (except those who can't work because their kids are off or they work for Jewish institutions). I'm pretty sure the poll to the right will confirm that.
I can't help thinking the halachic argument is an excuse for teachers & admins to take a week off while the rest of us work to pay their salaries. If we truly need to take this week off then it should be made up for on other days so that we can have the same number of school days as the public schools, who themselves have too few when compared to other countries.
Chag Sameach everyone!