Well, the way Greatschools does their rating is... it's kind of like they grade on a curve. So the schools in the upper percentiles are going to be a 10 and then decrease accordingly (I think the standardized test scores are the major factor in determining score). The top percentiles will always be a 10, and the bottom percentiles will always be a 1, just based on comparison across the state. So, if every school in the state started to have lower scores, the top schools would still be a 10 based on percentiles, even if their scores weren't as good as the year prior. (I hope I'm explaining that in a way that makes sense).
The greatschools ratings don't compare across states, but WA state has pretty good schools compared to the rest of the country. So a 10 in WA is really really really good (it's kind of like the difference between being the top student at a school where most of the kids are failing, versus being the top student at a private prep school where everyone excels)
I would say that the main reason why the scores may have dropped a little is because once a school becomes well known as being excellent, a lot of people will flock to the district to enroll their child(ren) into that school. The Lake Washington School District is having this problem right now, where they can't even keep up with the amount of kids entering, that class sizes have swelled dramatically, and I wouldn't be surprised if this translates into some of the schools ratings dropping in the future (for the simple reason that the teachers can't focus as much on individual students, and their budget is being stretched thinner to accommodate the influx). OMG, the cost of houses in the Rosa Parks Elementary district has increased insanely just because of that school!
Blackwell is still a really good school though (as many of the schools in Samammish are)! It's just that there are a LOT of good schools out here! It's pretty competitive!
