A key aspect of the Gates Foundation's U.S. efforts involves an overhaul of the country's education policies at both the K-12 and college levels, including support for teacher evaluations and charter schools and opposition to seniority-based layoffs and other aspects of the education system that are typically backed by teachers' unions. It spent $373 million on education in 2009. It has also donated to the two largest national teachers' unions. <answer>The foundation was the biggest early backer of the Common Core State Standards Initiative.</answer>
It was an early backer of what 
The foundation was the biggest early backer of the Common Core State Standards Initiative.