It is high time to correct a common misimpression: teaching isn’t the relatively leisurely occupation many people imagine, enviously invoking a nine-to-three school day and long summer vacations, which in reality seldom exist. We think of no other white-collar profession in terms of a single dimension of job performance. We don’t, for example, regard lawyers as “working” only during the hours they’re actually presenting a case before a judge; we recognize the amount of preparation and subsequent review that goes into such moments. If teaching is such a plum post, we might ask ourselves why attrition rates are so high.
Every single country that outperforms us has significantly smaller teacher workloads. Indeed, on the scale of time devoted by teachers to in-class instruction annually, the United States is off the charts. We spend far more hours in the classroom on average, twice and nearly three times more in some cases, than teachers in any other OECD country save Chile. Finnish high-school teachers, for example, clock 553 hours in the classroom each year. In Japan, home of jugyokenkyu, that number is 500. In the U.S., it’s 1,051. (Figures for elementary and middle school show roughly the same skew.)"
— Sara Mosle, from “Building Better Teachers" in the 9/14 edition of The Atlantic