apparently, "liberal bias" means anti-racist

Conservatives See Liberal Bias in Class -- and Mobilize

Complaints That Teachers Push Liberalism Are Trickling Down to the K-12
LevelConcerned that public schools are becoming sites of liberal indoctrination, activists have generated a wave of efforts to limit what teachers may discuss and to bring more conservative views into the classroom.

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The examples that were given of anti-conservative bias is that the schools cited would not allow anti-Islamic rhetoric to be preached! Incredible! This is truly getting to be utterly absurd! Teachers aren't going to be able to teach anything anymore if the conservatives have their way!

More on this from Americablog