This is Sister Marie Gemar's 44th year of teaching and her 40th year at Columbus High School in Waterloo.
But Sister Gemar didn't want to be an educator, she wanted to be a nurse until she joined the convent.
"The Sister who was in charge of the secondary school said you're going to be a teacher. I said no, I want to be a nurse and she said you're going to be a teacher and you have to teach for five years," said Sister Marie Gemar.
She admits she hated teaching at first, but then she said something changed.
"I realized you have to be in charge, but you can be yourself," said Sister Gemar.
Sister Gemar she owes a lot to her former teacher.
"I asked her why she wanted me to be a teacher, and she said I thought you had an inquiring mind and would always come up with new ideas. I'm so grateful she saw that in me," said Sister Gemar.
At Columbus High, Gemar mostly taught biology.
Twelve years ago, she started a forensics course, which is a lab-based class. Students like Regan McLaughlin enjoy the Sister's hands-on classes.
"She isn't just a great teacher, she's also a great person and role model to look up to," said Regan McLaughlin.
During the last four decades, Sister Gemar has also worked with students outside of the classroom.
"I coached volleyball for 23 years. I coached golf for 28 years. I did National Honor Society a couple different times," she said.
Sister Gemar said she'll miss a lot when she leaves Columbus, but she'll mostly miss her students. They feel the same.
"She will be greatly missed here at Columbus," said McLaughlin.
"What I will say to Columbus and Waterloo is I will carry you with me. This has become home, and it will be hard for me to leave," said Sister Gemar.
Sister Gemar plans to move to Dubuque to be the Community Minister at the Mother House for Retired Sisters.
She also plans to develop about 80 acres of prairie -- using her Masters of Earth Literacy degree from St. Mary of the Woods in Indiana.