Even when schools kept tutoring in-house, they faced their own issues. In Nashville, Tennessee, district officials initially looked for volunteers, retired teachers, college students, and others to serve as tutors. But these people proved difficult to find and train, according to a study coauthored by Kraft. Nashville schools ended up largely relying on their own teachers and staff. Yet teachers had little free time during the school day, so many tutoring sessions were done before or after school — rather than during the school day, a key tenet of the high-dosage tutoring model.