The dominant view of the purpose of education today is that schools should improve the absolute level of performance of children on well crafted tests of their academic ability in various subject areas like reading, writing, mathematics, and science, and to maximize the percentage of students who go to college.
The trouble is that to a great extent these kinds of tests are basically proxies for IQ. Yet, one of the most thoroughly replicated results in academic and institutional studies of K-12 education is that there is very little, particularly at higher grade levels, that educators can do that have a meaningful impact on any outcome closely related to IQ.
The worst of the worst schools, like West High School in the Denver Public Schools in recent years, can prevent even gifted and talented children from reaching their potential by leaving them unprepared to go to college and causing them to fail to go to college. But, by and large, merely mediocre high schools don't do much harm, and even quite good high schools don't help much.
Furthermore, it is a cold hard fact of life that many high school students should not be on a college prepatory track. IQ is sometimes overrated. But, the one thing that IQ is an excellent predictor of is academic success in schools and colleges. One can quibble over where one should draw the line, but a child with a below average IQ, and that includes 50% of all high school students, is unlikely to be able to start college without remedial work, is unlikely to graduate from college, and is unlikely to benefit much from attending college classes.
Maybe, instead of scouring the educational landscape for the magic bullet that will allow high school teachers to raise the IQs of their students, a more realistic mission for public schools is in order. Education does socialize students into a culture. We can teach kids to cooperate with each other, to develop ways of responding to authority, to function in bureaucracies, and to self-organize and be self-reliant.
It is also a situation where societal resources could be more closely matched to realistic life and career prospects for students, giving students skills and training that will be relevant to their lives.
But, as a way to get more students to achieve in formal academic tasks at some specific level - say, ready to perform academically at the level of a 1980 college freshman at a four year flagship public college - there are real limits to what it can accomplish. One can prevent the curriculum from being unduly watered down for students who are capable of achieving at that kind of level, but can't necessary do all that much to increase the size of that pool of students.
It is possible to greatly increase college attendance for academically able high school students, but the primary barrier there is lack of financial resources, not a lack of academic preparation for college among students who have a realistic shot at completing a college education. If higher education funds are targeted at this sweet spot, we can get far greater results than expecting the K-12 system to do something that we know it is ill equipped to do.