At 79, Mike Hilton, a teacher at Umpqua Valley Christian School, has taught math for 40 years and has no intention of quitting any time soon. In January he will take on an extra assignment as a Roseburg city councilor. Hilton said he tried retirement after 33 years of teaching math in Edmonds, Wash., near Seattle, but found it boring. “Retirement isn’t what it’s cracked up to be,” Hilton said. Hilton teaches calculus and pre-calculus to juniors and seniors. The students are his favorite age to teach, he said. “They’re bordering on adulthood, and I just get along well with …