From the Wisconsin Center for Education Research report:
Educational equity issues within the school district [MMSD] are the source of much public controversy, with a relatively small but vocal parent community that is advocating for directing greater resources toward meeting the needs of high achieving students. This has slowed efforts to implement strong academic equity initiatives, particularly at the middle and early high school levels.
From Matthew Yglesias:
The rhetoric of No Child Left Behind is, I think, an appealing one. The idea is that, well, no child should be left behind. It’s an essentially egalitarian aspiration — the school system should try to do well for the hardest to teach kids, included ones coming from difficult backgrounds and ones who simply for whatever reason have a hard time with school. The idea of “gifted” programs is basically the reverse vision — that the school system should focus on the easiest cases and push them to the highest level of achievement possible.
There’s not a stark either/or choice between the hard cases and the easy cases, but at some level you do need to make a decision about priorities. Insofar as we’re serious about educational equality, that will to some extent involve shortchanging the best and the brightest. Insofar as we’re serious about taking the most talented as far as they can go, that will involve shortchanging equity. The former strikes me as more desirable than the latter, especially for people who want to think of themselves as being on the left.
From Michael Bérubé:
If we as a society are going to make decisions concerning prioritizing scarce educational resources, it makes sense to me, for us to consider what kind of output we desire. Do we want to, for example, maximize the number of future American Nobel prize winners and enjoy the fruits of the breakthroughs that our most gifted can achieve, or do we want to maximize the educational level of the median American worker? Both results have great value, and if we were to quantify them in terms of dollars, I’m not sure which one would prove to be of greater value to society. But I think these are the questions we should be discussing. And that devoting our resources to maximizing the future opportunities of our least educationally apt children for the sake of doing so, without examining the costs, is fuzzy-headed. Which may or may not be a liberal value. But as liberals we do acknowledge that society is not just a collection of disparate competitive individual maximizers, but that we live in a community where cooperation is also an important value. And that maximizing the strength and resources of that community is itself a liberal value.
The National Access Network just reported that “the United States now has the highest relative childhood poverty rate among developed countries.” When the test scores of white American students are reported separately and compared to the test scores of students in developed countries, the United States ranks third highest. In contrast, if Hispanic and African American test scores are compared to the same international scores, the United States ranks last and next to last. It noted that “the authors of a 2001 Wisconsin study concluded that a weighting of 3.4 times the base cost for education was needed for poverty students to reach state standards.” In a new paper on class size reduction efforts, research found that “Wisconsin SAGE class-size reduction experiments showed positive effects on student performance, especially for disadvantaged students.” Economists estimate that reduction efforts targeting disadvantaged schools nationally would cost about $2 billion, and as the evidence shows, it would reap many benefits.
Robert Godfrey
AMPS 
Do we really need to cast kids’ aspirations as a zer0-sum outcome the puts various groups of kids’ needs against one another?, Instead, how about a goal that all children get a fulfilling, challenging education that prepares them for life and allows every child to pursue his/her full potential.
“Equity” is not contrary to appropriate TAG programming. Better to familiarize yourself with the literature about the risks of drop-out, depression, etc by high-aptitude kids who are bored or frustratred by school. And keep in mind that too many highly capable low-income and minority students do not have access to outside/private enrichment opportunities. Shouldn’t they have access TAG programming to support their motivation, interests, abilities and allow them to fulfill their potential?
An “equitable” curriculum should not be confused with the concept of an “equal” (i.e. identical for all) curriculum.
In the same way we encourage our kids to respect diversity in race, gender, religion, sexual orientation, physical ability/disability, etc.. As well, kids should not be pawns in a social engineering experiment that denies individuality and uniquenesses — be they in the arts, sports, or academic interests or even aptitude.
I don’t think any of the quoted sources “cast[s] kids’ aspirations as a zero-sum outcome.” What they are discussing is the reality that resources are zero-sum and this creates hard choices. Resources are (barely) sufficient that we can so some of both — programing for high achievers and increasing the likelihood of success for low achievers — but it is impossible to fully fund, and getting more difficult to adequately fund, both.
Places like Rockville Centre, NY have dramatically increased the achievement of low income and minority students and created more high achieving low income and minority students in part by eliminating ability grouping, and instituting what they call Universal Acceleration. I believe this is the sort of thing the author of the first quote is referring to and it certainly has been resisted in Madison.
Whether we like it or not, public education is an experiment in social engineering, the question asked by the second two quotes is what sort of society do we want to try to engineer.