From selecting appropriate curricula and teachers to providing classrooms with bathrooms easily accessible to 4-year-olds, public preschool programs present challenges to districts that run the programs, which are designed to prepare children to get off to a good start when they enter kindergarten. While a wide range of private preschool programs exist, public programs usually are free for parents who enroll their children in them, and the growing number of public programs reflects recognition by educators and parents that they improve the readiness of the children for kindergarten and the grades that follow. "The school readiness component is one of the most important aspects of preK programs," says Davida McDonald, director of state policy at the National Association for the Education of Young Children (NAEYC). More districts are seeing the advantages of school readiness and preparing youngsters for their K12 careers. Administrators say children who participated in public preschool programs seem uniformly to surpass children who don't participate in basic learning programs before they enter kindergarten.