The annual honour recognises US educators from kindergarten to 12th grade who have "demonstrated monumental impact on the lives of students and who embodies the highest standards of the profession".
The award includes a US$10,000 ($14,300) prize.
Herzfeld said she should take little credit for shaping her teenage students, as she just laid the foundation by insisting that honesty - onstage and off - be a guiding principle.
"These kids are so close to adulthood they can taste it, but they don't have all the responsibilities of adulthood yet. So it's important to give them a safe place where they can fail or experiment and it doesn't matter.
"I want them to feel confident enough to call out any adult, any bureaucrat, any politician, anyone, even their teacher. They need to speak truth to power."
Heather Hitchens, president and CEO of the American Theatre Wing, said Herzfeld was a great example of so many teachers doing great work under all kinds of difficult circumstances.
- AP