For US students, which hampers students more out of class size, the media, or laziness?

It is no mystery, when you average out the scores on the planet, students K-12 in the US wallow around the middle of the pack. I often hear in the news parents protest school closings because it could lead to larger classes in the surviving schools. Is that just an excuse? Japan and Korea have on average 10 students per class more than the US and yet they still beat the stuffing out of Yankee students. Doesn’t that say something about the amount of students in a class not being the problem? The media always bill teacher and students as enemies, the teachers out to get the students, and the students trying to get over on the school, is that it? Are Yankee students just too lazy, caring more about video games, hanging out, and making out than study?