Beavertonian here, so not that far from you. Since this teacher started showing symptoms on the 19th that means it's been passing around for maybe 2 or 3 weeks already - bit of a scary thought.
Since kids are only developing a very mild illness from this, it seems most likely that this teacher caught it from one of the students.
I've noticed people in Beaverton/Hillsboro are really bad at washing their hands in public. I'm at the movies a lot and every single time I go to the bathroom there's someone walking right out. I've been seeing a few people with masks on (although way more when I was in Toronto three weeks ago), but like those wont help you at all if you're not washing your hands.
While I appreciate the firsthand information, I think this is true of practically anywhere. Frankly, trying to prevent catastrophe through changing individuals’ behavior is practically impossible. Consider the amount of people who still smoke cigarettes as an example.J
Also on the MAX, cough and sneeze without covering it or on hands then touching everything that others will be also touching. Maybe all trains are like this?
Since kids are only developing a very mild illness from this, it seems most likely that this teacher caught it from one of the students.