For the last decade, in districts big and small, the Bill & Melinda Gates Foundation has emerged as the largest private funder of educational efforts. This began with an initiative around small schools in the early to mid-2000s, mostly abandoned now, and has gained traction in the past few years in areas such as teacher evaluation, the Common Core State Standards and district-charter collaboration. At a time when schools are more strapped financially than ever, it's hard for districts to refuse money from the foundation when offered, although it often comes with strings attached asking districts to follow reforms pushed by the foundation, including teacher evaluations and district-charter collaborations. Six districts--Denver, Pittsburgh, Tulsa, Atlanta, Memphis and Prince George's County--and an additional network of four charter management organizations in Los Angeles, have received grants from the Gates Foundation to put into place a three-part teacher evaluation system that incorporates feedback from principals and peer evaluators along with measures of student achievement. The foundation also provides funding for veteran teachers to serve as full-time mentors for those new to the profession.