THE COST of K–12 public schooling in the United States comes to well over $500 billion per year. So, how much influence could anyone in the private sector exert by controlling just a few billion dollars of that immense sum? Decisive influence, it turns out. A few billion dollars in private foundation money, strategically invested every year

Hundreds of private philanthropies together spend almost $4 billion annually to support or transform K–12 education, most of it directed to schools that serve low-income children (only religious organizations receive more money). But three funders—the Bill and Melinda Gates Foundation, the Eli and Edythe Broad (rhymes