LOUISVILLE, Ky. — School districts across the state are struggling to find enough teachers to lead classrooms. With a new incentive, some seasoned vets are stepping up to fill the void.

Walking around Glenn Zwanzig's classroom, you can find students collaborating through a hands-on lab to learn more about inertia. He walks table-to-table making sure they understand the assignment. When they don't, he offers help. When they do, he talks with them about how to conceptualize what they just learned and apply it to real-world situations.

The students probably realize he's good at his job, but they may not understand why. Mr. Zwanzig has 35 years of teaching experience. He retired in 2017.

When asked what made him come back after several years out of the profession, he jumped right in with a swift and simple response.

"These guys," he said, pointing to the students behind him.

Mr. Zwanzig had been substitute teaching some since his retirement. That's what initially brought him to Meyzeek Middle School. They were down a teacher at the beginning of the year, so he was filling in as a substitute.

“When I got in here, I quickly fell in love with these guys. They were looking for teachers and there was just nobody out there,” said Zwanzig.

During Kentucky's special legislative session, lawmakers passed a provision allowing retired teachers, like Zwanzig, the chance to return full-time without impacting their pensions. It was a financial incentive he just couldn't pass up.

“What’s funny is, after I had been here a couple weeks and we decided I was going to stay, when I announced that, every class stood up and applauded me. They made me feel good about staying,” said Zwanzig.

Due to the statewide teacher shortage, school districts can temporarily go from hiring just 1% retired teachers up to 10%.

For Zwanzig, that meant leading a middle school classroom after spending the majority of his career teaching at Manual High.

“The biggest challenge has been adjusting to the energy of the kids," said Zwanzig.

Right now, he said this is exactly where he wants to be.

“I really retired too soon. I miss it so much. Once I got back with the kids, I liked that they need me and that makes me feel good. I get excited to be around the kids," he said.

As for if he will continue to teach full-time beyond this year, he said that isn't up to just him as he also has family to consider.

"They have lost a lot of my attention now because this is a full-time job. From the time I get up to the time I go to bed, most of the time, I am working on school stuff," said Zwanzig.

Jefferson County Public Schools has hired 44 retired teachers under the Senate Bill 1 critical shortage effort. As of early Nov., the district had 187 classroom vacancies.