A few things that would help right away, uniforms and tiers. Three or four tiers would do. Slow, average, bright. I understand the mixing of students of different abilities, but I think it does more harm than good.
When I was seventeen years old, I took the best class of my life. It was a science fiction/fantasy literature class elective, half a year long. I'd had the teacher the year before for AP English, and I assumed that perhaps the class might be as good if I didn't have to deal with the out-and-out retards that came with the subject of science fiction. We had the violent kids who fantasized about being evil dictators, the obsessives who didn't know when to shut their mouths... All the "special" kids who I'd stopped seeing in the eighth grade when it was determined I was better than them and shouldn't have to spend my time dealing with them. (Like dealing with the typical honors student is any less frustrating.)
Instead, our teacher barged ahead from the first day, without stopping for anybody or anything. The stuff he was teaching was alien to all of us: Propp's hierarchy for fairy tales was first on the list. He'd give us a book and a set of short stories a week and expect us to finish it all. While we read perhaps eight books all year in my IB English class, we got to at least ten in the sci-fi course, all in half a year, and we weren't dealing with bullshit sci-fi, we were dealing with the stuff that's complex and heavy enough to qualify as Serious Literature in my book.
How he achieved it: He had no lesson plans, he gave no tests, he did nothing but talk, using the things we were reading as a frame of reference. He'd do research so that he knew more than any of us (he crammed for Asimov, who I know inside and out, and came up with things I hadn't heard of before), and everybody just talked. There was no monitoring, no belittling, no talking down, just an hour-long conversation every day, with four big projects that determined our grade - but the projects were freeform; we could decide how to handle them. I wrote prose and poetry; three kids made a documentary; a bunch of the kids I'd detested went into Garry's Mod and recorded a pantomime; other kids made large cardboard replicas of alien figures and devised their own SF worlds.
Again, these were not honors kids. They were kids I'd thought were too stupid to read. But they handled the courseload as well as anybody, and left with a pretty hardcore understanding of how sci-fi works.
I have never had much success in school. I'm the kid who got placed in all honors courses because teachers realized I was a faster learner than their other students, but who spent his time in school refusing to get much schoolwork done. Before I discovered art school, which cared more for my portfolio than for my GPA, I was at a good public school, which in the minds of friends going to good private schools was a shithole. I endured a year of snide comments and mockery from people I'd gotten along with who were more-than-delighted to remind me that society had determined my "place" was in a public school with no famous alumni. Now that I've transferred to an excellent art school, all the comments are something along the lines of "Can I have a tall latte with milk?", which was funny about twenty years ago.
I find it unbearably offensive that society makes attempts to "rank" students. Yes, people are different, and learn differently, but those are strengths unless decided otherwise. I know a lot of people whose lives were ruined by well-meaning administrators who assumed children were shitty brats who needed disciplining and straightening out. What would help right away was a system that made an attempt to welcome diversity, not just in appearance (seriously, screw uniforms, they're fixing the wrong problem) but in character and style.
There are similar schools in the States (Carolina Friends school in Chapel Hill comes to mind), but most of them are very, ridiculously expensive (as much as a private college in the U.S.).
http://www.economist.com/displayStory.cfm?Story_ID=E1_TTGNNP...
I think your experience is unusual in that you would have chosen easier classes left to your own devices. Usually, the debates about "tracking" center on the weaker students getting pushed out of the harder classes. What I remember seeing is that the countries with strongest schools (Finland and I think Singapore) just set a given pace for each class, and let students and parents decide what is best for them.
That's why you would have different tiers. To help each student as much as you can at his or her own level. "Lower" tiers focus more on practical and artistic matters, while "Upper" tiers focus more on theoretical and intellectual matters. Note that countries that have such a system generally refer to it as columns, not tiers, because that name does not do it any justice.
It doesn't really solve the major educational problems (e.g. parents), but it does help to take the diversity of children into account.
My point is that students don't have levels. When I was in middle school, I was somewhat brilliant at math. (Not honking my own horn, but it's true: I was a beast.) I could handle pretty much anything that required formulas and logic and calculation. Once I got to high school, I had a slew of shitty math teachers, and an incredible English/humanities department, and so I shifted focus and found where I was happiest anyway. While I can handle left-brained stuff, I really shine when I'm dealing with hazier, foggier stuff and giving it meaning.
One is not better than the other. I have friends who are way over on one side who are just as bright as I am. My cofounder, for instance, is a massive Linux geek who is completely at home messing with code and fixing it up. The stuff that I do primarily online, design, he treats as a hobby. I treat learning to code as a hobby, meanwhile, while that's what he's studying. I'd never presume to call my job more important than his is, and vice versa. People are different. It's okay to like completely different things. It doesn't make you lower or higher in any way.
For example my little sister (18) is an artist who just got into Cal Art's Animation program not though grades rather she built an awsome portfolio. This summer rather than getting a minium wage job she held an art show and made more than minium wage doing what she loved. Yet, she was also the validictorion of her highschool, and took 7 AP test's getting a 5 on each of them.
Suggesting she has as much drive and talent as a normal highschool student is just stupid.
What we need is classes that move quickly, classes that move slowly, and the ability to move /freely/ in between without stigma. That, and higher standards for /everyone/.