The basics: Cherie Williams-Muller, 59, of Fresno, is a recently retired adaptive physical-education teacher for Fresno Unified School District. She has two sons, Randy C. Williams, 23, and Paul Williams, 20.

What she does: Before retiring in June, she started a campaign at Powers-Ginsburg Elementary School to raise money for Rifton Adaptive Tricycles, which provide therapeutic, reciprocal exercise with all the fun of riding. The trikes are designed for students with special needs, including those with cerebral palsy and muscular dystrophy. Each one costs about $1,500.

Why she does it: Fresno Unified has some adaptive trikes, but they are heavily used and worn. Williams-Muller worked 30 years in the district, 11 in adaptive P.E.

The Turning point: Her oldest son, Randy, has cerebral palsy. She was told he wouldn't be able to walk. At an early age, he began working with reciprocal intervention and walking with support. The Rifton Adaptive Tricycles have high back support and a handlebar close to the rider. Randy is now ambulatory.

"I know these tricycles work and can be beneficial to students," she says. "These trikes help strengthen their brain. The reciprocal intervention of cycling helps them to use the right and left sides of their brain and legs for full range of motion."

Details, details: Williams-Muller started the campaign by selling chocolate bars. The campaign received a boost when inmates at Valley State Prison for Women in Chowchilla pooled their resources to donate $800. The Chicano Correctional Officers Association also has chipped in $200. So far, the campaign has raised enough money to buy two tricycles.

What others say: Angela Molander, a special-education teacher at Powers-Ginsburg, says Williams-Muller has helped students with orthopedic impairment also get involved with Special Olympics and California Classic events.

"She understands this world and has a huge heart," Molander says. "At her retirement, she wanted any money to be given toward the trikes. She has nothing but heart."

How you can help: Donations can be made to the Powers-Ginsburg Parent Foundation fund for the tricycles. The school is at 110 E. Swift Ave. Service organizations also can arrange for video presentations on the need for the tricycles. Details: (559) 285-6011 for Williams-Muller or 248-7230 for Powers-Ginsburg.