Warren hasn't always described this pivotal moment in her career in the same way, a point that has prompted some media outlets to question whether she was in fact fired. In her telling, Warren was "shown the door" by the school principal in 1971. If that hadn't happened, Warren has said she might well still be a public school teacher. The presidential candidate spoke exclusively with CBS News' Zak Hudak about that story and why it has evolved.

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