Ethnomathematics. I never even heard of it until I read Diane Ravitch's piece in this morning's WSJ (subscriber link; excerpt at Free Republic), but I don't know why I'm surprised. They cite a work by Williamson Evers and Paul Clopton showing how curriculum has changed in between a 1973 algebra text and one in 1998 for "contemporary math".

In the 1973 book, for example, the index for the letter "F" included "factors, factoring, fallacies, finite decimal, finite set, formulas, fractions, and functions." In the 1998 book, the index listed "families (in poverty data), fast food nutrition data, fat in fast food, feasibility study, feeding tours, ferris wheel, fish, fishing, flags, flight, floor plan, flower beds, food, football, Ford Mustang, franchises, and fund-raising carnival."

But the first link shows you that, as Ravitch points out, things have gotten much worse from there. Algebra is a form of oppression.

Now in the twentieth century, this distinction is manifested in the contrast between the "academic" mathematics that is taught in schools, which allows an elite to assume management of a society's productive forces, and the "everyday" mathematics, which allows individuals to function effectively in the world.

This is not just twaddle, but dangerous twaddle, as Ravitch points out.

It seems terribly old-fashioned to point out that the countries that regularly beat our students in international tests of mathematics do not use the subject to steer students into political action. They teach them instead that mathematics is a universal language that is as relevant and meaningful in Tokyo as it is in Paris, Nairobi and Chicago. The students who learn this universal language well will be the builders and shapers of technology in the 21st century. The students in American classes who fall prey to the political designs of their teachers and professors will not.

Every fact to the cultural relativists is subject to spin; no fact is neutral to them. There is no desire to teach anything beyond what is "everyday math" because they do not believe it is necessary for students to understand the vertical connections between fields of math, which is why we taught algebra before geometry before trigonometry before calculus. I don't know that it's because educators are trying to create borgs for social justice or if they simply haven't been educated well enough themselves to understand the reason traditional or "academic" math has been taught as it is.