For 12 years, Dave Sanderson has been living a double life.

Sanderson, chief executive of Wesley Day Advertising in Des Moines, sheds his corporate persona at the end of the day to slip into the role of college instructor at Simpson College in Indianola, Iowa.

It's the thrill of being able to share his years of experience with a classroom full of mostly older students, who also have committed to being in class after a long day of work, Sanderson said.

"I enjoy what I am doing in the real world and want to share that," he said. "And I like being up in front of a class showing off."

Sanderson is part of a group of about a half-million adjunct professors nationwide who shore up college and university faculty rosters. Adjuncts — part-time nontenure-track faculty — are paid little and don't receive traditional benefits from the school, but often find professional and personal rewards from teaching.

David Dahlquist has long incorporated teaching college into his life's work of designing and creating art. As an adjunct, he teaches college-credit art courses to students at Grand View College and Des Moines Area Community College, even while maintaining his job with a local architectural firm.

"It's personally rewarding to teach, and it brings new views back into your business," he said. Architectural firm RDG has a lot of talented and creative people who are able to share their experiences through teaching, Dahlquist said. Sometimes those workers visiting his classes provide for "great exchanges," he said.

As a businessman, Sanderson said teaching keeps him sharp. It's a chance for him to share what he's learned from more than 25 years in advertising.

"In advertising, a lot of people in our industry blow smoke and get away with it," he said. "You can't go into the classroom and blow smoke. You have to know your stuff."

Karen Tegtmeyer, owner of Model Technologies Inc., a software development company in Johnston, Iowa, said she was able to "add real-world knowledge" to her students' learning by teaching a computer science class at DMACC last fall.

"I was able to bring a different perspective to them," Tegtmeyer said.

Her investment — three hours of class time a week and many more hours of prep time — eventually could pay off for her business by providing prospective employees who have taken her class or who have spread the word about the company, she said.

For most adjuncts, the intangible rewards are worth the extra efforts — and minimal pay.

"I certainly don't do it for the money," Sanderson said. The $2,500 he receives each semester for teaching an entry-level advertising course "buys me Christmas lights because I'm into that."

Drake University's College of Business and Public Administration, like many of Drake's academic schools, uses adjunct professors on a regular basis, said Charles Edwards, business school dean.

"Typically 5 to 10 percent of faculty is visiting or adjunct professors," he said. The business college has had five or six adjunct professors a semester and as many as 14, he said.

The business school adjuncts help provide professional perspectives with their real-world experience, Edwards said.

"Adjuncts are some of our more popular teachers," he said. "There is nothing like real-world examples, and students know and appreciate that."

Patty Cox is that kind of real-world example for University of Iowa graduate nursing students. She supervises the students at the Iowa Health Clinic in Ankeny. The nursing students, who need clinical experience to graduate, work with Cox, who also is an adjunct instructor with the U of I College of Nursing.

"I see it as a chance for me to give back my time and talent to the profession," she said.