SAN DIEGO -- Former students of retired teacher John Corcoran think of him as an exceptional educator, even though they were shocked to learn about his inability to read and write.

Corcoran managed to make it through school, college and 17 years of teaching before taking classes to become literate.

Cheri Dixon took Corcoran’s bookkeeping class at Oceanside High School in the late 1960s. Despite his deceit, she still has high regard for him.

"He was an excellent teacher and I still carry those skills with me," Dixon said. "I do remember him. He vividly sticks out in my mind."

Dixon, also a retired teacher, said she remembers nothing out of the ordinary about the way Corcoran taught.

"He made everybody feel very comfortable and you really got something out of the class," she said.

It was not until much later that Dixon learned Corcoran was illiterate. Looking back, Dixon said things started to make sense.

"I was shocked. I was shocked and then I was like, 'well now it makes sense why I was the class secretary.' I did the roll call and read the bulletin. I was like, 'okay... makes sense,'" said Dixon.

A look inside Dixon’s yearbook revealed no picture of Corcoran, but he did write a simple message. Next to a blank picture Corcoran wrote: "Best of Luck... John Corcoran."

When asked about the writing, Corcoran said he memorized a few words and often used a cheat sheet with common phrases.

"In grade school I learned penmanship like an art form," he said.

Dixon can’t believe Corocan got through most of his life without the ability to read and write.

"As a teacher for more than 30 years, I can’t imagine running a classroom without being able to read or write," Dixon said.

Former student Danny Kelso, who now lives in Georgia, also has a great respect for Corcoran. He recalled how different Corcoran’s classes were.

"Everything was either multi-media presentations or speeches or roundtable discussion. When we had reports that were due they were given orally," Kelso said.

Despite the deception, Kelso admires Corcoran and said the teacher truly inspired him.

"I really do feel like he was one of the better teachers that I had. He kept us inspired; he kept us thinking," said Kelso.

John Corcoran has made it his life’s work to help others in his situation. Now an education advocate, he strives to improve the education system.

"I think illiteracy is a form of child neglect and child abuse. I mean that deeply. I plead their case," said Corcoran.

Corcoran encourages parents and teachers not to overlook children's problems so they're not pushed into a life of cheating.