Education Secretary Arne Duncan tried Monday to quell the outrage sparked by his comments that injected race and class into the debate about the Common Core academic standards taking root in classrooms across the country.

Duncan said Friday that he was fascinated by the fact that some opposition to the standards was coming from "white suburban moms" who fear that "their child isn't as brilliant as they thought they were."

The remark lit up social-media sites, prompting pointed responses online, an open letter from a school superintendent, digital images of Duncan's official federal portrait with the word "bigot" emblazoned across it, and one congressman's call for Duncan's firing.