Andrew Quinn, sadly a thirteen year old who considers himself liberal and progressive even though he is quite smart, is having a crappy experience in school. I completely understand his experience.
Luckily I spent most of my schooling in the United Arab Emirates at a very good American school where tiered classes began in second grade and were also imposed on social studies and science. Only when I came back to the U.S. for tenth grade did I discover that the tiers had somehow collapsed.
Andrew is right, there is no reason for a student at the academic top of a subject to be in the same room with a student at the academic bottom. The one at the top gets bored or misdirected and the one at the bottom usually gets frustrated by being compared to the top.