INDIANA -- One of America's best teachers is proof that adversity is no match for perseverance.
"Speak out, what are you thinking, what are you feeling? What's in your head? What's in your hearts?" says Kathy Nimmer standing in front of her class.
Most people have that one teacher they will never forget.
For many students at Harrison High School in West Lafayette, Indiana, that teacher is Kathy Nimmer.
Nimmer is blind. When she started, more than two decades ago, it was such a struggle she almost gave up.
One expression she used was that chaos reigned.
"I'm remembering the day a student threw a book bag across the room and it shattered a window and it felt like it was shattering my heart," she said.
One day, she had a revelation.
"It's not about vision, it's about connecting with students at the heart level," she said. "That's what it is. Because they won't learn anything more from a sighted teacher if that sighted teacher doesn't care about them as people."
That philosophy helped her become one of four finalists for the 2015's National Teacher of the Year award.
Nimmer, who began losing her sight in second grade, navigates the halls with the help of her guide dog.
Students volunteer with their names, instead of raising their hands.
"I have my classroom laid out so I'm never further than three desks away from the most distant student," she said.
There are advantages to being a blind teacher, Nimmer says.
"Yeah, oh my goodness. The best one is I can't see them," Nimmer says laughing. "Which sounds ridiculous, but it means I can't judge them."
Katie Bond says English wasn't her strongest subject, until she took Nimmer's class.
"She just sees the gold in people and brings that to the surface," Bond said.
Nimmer's days were once filled with tears.
Now they are filled with some of the nation's best teaching -- by someone who sees her students for who they really are.