Philanthropic interest in K-12 education has grown substantially in the past 10 years, with some estimates putting K-12 educational spending at 25% of all philanthropic giving. Critics have pointed to the lack of educational expertise held by philanthropists and the intrusive nature of their giving, calling them a small group of billionaires promoting privatization, deprofessionalization, and high-stakes testing as fixes for American public schools. Others say it's not so simple. Funders have a diversity of perspectives on charter schools and other initiatives and do not march in lockstep. But all agree their influence is growing.