Low US education rankings: too much attention to sports, media, or shopping?

http://www.washingtonpost.com/local/education/teacher-assails-practice-of-giving-passing-grades-to-failing-students/2015/05/17/f38f88ae-f9ab-11e4-9030-b4732caefe81_story.html

I’d hate to be a teacher in this setup -
“… He was given a pre-calculus class with 38 seniors at H.D. Woodson High School. When he discovered that half of them could not handle even second-grade problems, he sought out the teachers who had awarded the passing grades of D in Algebra II …”
“… “Huh!” Rossiter quoted the teacher as saying. “That boy can’t add two plus two and doesn’t care! What’s he doing in pre-calculus? Yes of course I passed him — that’s a gentleman’s D. …”