Roger Cersine, a popular sociology and Advanced Placement history teacher at Washburn High School in Minneapolis for several decades, challenged his students to think outside of the box.

During a class in the late 1960s, he orchestrated a play-acted violent altercation with a student, which was witnessed by other students who believed it was real. Immediately afterward, he had students write down everything they saw. Cersine used it as demonstration of why eyewitness testimony is often unreliable.

Nearly two dozen of his former students left messages of gratitude and praise on his online obituary following his death from renal failure Dec. 7. He was described as the kind of teacher you never forget, and who inspired some to become educators themselves.

Cersine, who also was elected to the Minnesota State High School League Hall of Fame as a swimming and diving official, died at Sunrise of Edina senior living facility. He was 86.

"He had a great sense of humor that he used in the classroom," said his wife of 62 years, Barbara.

Cersine was born in Ely, Minn., in 1935 and worked in the iron ore mines and for the forest service. His father told him to "not get used to the good paychecks because you are going to college," his wife said.

After receiving bachelor's and master's degrees, he taught at several schools in north Minneapolis. He was a Civil War buff, and he knew he wanted to teach history. He eventually landed at Washburn, where he taught until 1989.

For over half a century, Cersine was a swimming and diving official at the high school and college levels. He served as the Minnesota State High School League Swimming & Diving rules interpreter for 35 years and helped organize the state's Swimming Officials Association in 1972.

Cersine also served on the National Federation of State High School Association's Swimming & Diving Rules Writing Committee and officiated men's and women's swim meets at the University of Minnesota, Big Ten women's and men's championship meets, NCAA championship meets and at the Special Olympics.

"Roger swam in high school, which started his interest in the sport," Barbara Cersine said. "He used to officiate our granddaughter's high school swim meets. He said he didn't know which was his granddaughter because all the swimmers wore caps."

Outside the sport and his work as a teacher, Cersine played a key role in the expansion of Minneapolis Federation of Teachers Credit Union to TruStone Financial, and he served on the TruStone financial supervisory committee, mortgage board of directors and board of directors for 48 years.

He was also an avid hunter and outdoorsman, and he took annual canoe trips in the Canadian wilderness. To get in shape, he and a friend would walk up and down hills with heavy backpacks.

"We went on a canoe trip on our first anniversary," his wife said. "I didn't think we would make it to our second anniversary."

Besides his wife, Cersine is survived by his son, Michael, of Edina, and his daughter, Amy Smith, of Bloomington.

Services will be held at a later date.