Coho: Here are some thoughts on your questions:
-School is not responsible for your child care at any time, if your child is sick you must make arrangements just like if they are on strike you must make arrangements for your childs care. Is it always easy or convenient, no, but it is still your responsability.
- there is no "cut date" for college enrollment, most people apply and many are accepted to college long before they finish their senior year of high school.
-High school athletics is an extracurricular activity. It is a privledge to play, not a right. You could not sue your school for lost opportunity to play any more than the school could sue you if your kid became ineligable and the team had a losing season because your kid couldn't play. Also most sports teams and thier coaches are playing even if the district is on strike. The schools think it is important for the kids to have the opportunity to compete, especially the seniors, even though most will never play after the end of high school.

As far as why teachers strike, well they do it for the same reason anyone strikes, to try to better their own situation. The fact that they are public employees does not mean that they shouldn't try and better thier own situation just like everyone else. They must think the market can handle a pay raise, smaller classes or what ever the demands are. I don't know if that is the case in this situation or not, but the market will decide.
I do know that in many parts of the country school districts are paying more than Washington and some even give substantial signing bonuses (as much as $50,000.00) if a teacher agrees to come teach in their district.

By the way I am not a teacher or nor have I ever been one.