Three hundred teachers and their supports have spoken out about the Bill & Melinda Gates foundation, citing its wide influence over the US education system. Activists have a website, Teachers’ Letters to Bill Gates, which provides a forum online for teachers to tell Gates how he affects their classrooms. They are looking to deliver the letters during a demonstration.

Some educators say that the Gates Foundation, through its initiatives and groups that it funds, has blamed teachers and their union for shortcomings in student performance while discounting the role of poverty. They also state that the Gates’ promotion of the Common Core standards, which has been fully adopted by Washington state among forty-four other states, is also to blame for poor performances.

On Wednesday the foundation did not respond to a request to comment on the protest, but on Thursday issued a statement saying it is “engaged in a constant conversation” with teachers here and around the country about how the foundation can help them.

“While not all teachers agree on how best to make that happen, they are all dedicated and passionate about their students,” the statement said.

Among the issues that most rankle the foundation’s critics is its support of using student test scores in judging teacher performance. Recently, though, the foundation sided with American Federation of Teachers President Randi Weingarten, who in April 2013 called for a moratorium on using Common Core tests for teacher evaluation.

“No evaluation system will work unless teachers believe it is fair and reliable, and it’s very hard to be fair in a time of transition,” Vicki Phillips, the foundation’s director of education, wrote in an open letter earlier this month calling for a two-year moratorium.

“The standards need time to work,” Phillips wrote. “Teachers need time to develop lessons, receive more training, get used to the new tests, and offer their feedback.”