When Jean Kelter Dills started teaching Jazzercise in Hood River, Ronald Reagan was president, she used 45-rpm records to play music, and Frank Arnold, one of her first students, was 58 years old.

Thirty-two years later, Jean plays her class’s daily music selections on an I-Pod. Her record player, purchased for $335, should probably be on exhibit in a museum. Her cassette and CD players (which followed the record player’s retirement) are collecting dust in her basement, and Frank Arnold is still attending class every week. At 90 years of age, his “jazz squares” and “chasses” may not be quite as graceful as they were in 1982, but what he lacks in form he more than makes up for in enthusiasm.