I would rather have seen her answer along the lines of, “of course I have, in fact every student I have ever worked with is his own unique personality and learning style. As a result, I have had to learn to teach to every single unique individual, to take into account his learning capability and style.”
Take the opportunity to define Diversity for the interviewer and leave race out of it.
Exactly the right answer. I know these people. They use "diverse" as a synonym for "non white". But then it's also a trap, because the interviewer was correct: a roomful of Hispanics is not actually diverse, ethnically speaking. The correct answer would be use the question to showcase how you treat everyone as a unique and valued individual, regardless of race, ethnicity, etc. If they want to come back and say, but what about X, Y or Z ethnic groups, then at least they've had to expose their own narrow-minded view of diversity in the process, while you have had already taken the opportunity to tout something good about yourself.