what are the reasons that mama is considered a radical teacher?

She does don conform to racial stereotypes.

She blanks out racially offensive ideas in textbooks

She is extremely strict

Holds kids accountable no matter what their background

Mama also glues paper over a chart in one of the books despite Mrs. Crocker warning her it could mean trouble.

Mama's refusal to teach racist history makes her a maverick of sorts with other teachers.