When the school year starts Tuesday, Loudoun County will have two new elementary schools: Discovery Elementary and Moorefield Station Elementary, both in Ashburn.

James Dallas, 49, is the principal of Discovery, which will have about 650 students drawn from five schools: Steuart Weller, Mill Run, Creighton’s Corner, Dominion Trail and Hillside. For five years, Dallas has been principal of Cedar Lane Elementary in Ashburn. Before that, he spent 19 as a teacher, principal and administrator in Fairfax County.

Karen Roche, 46, is the principal of Moorefield Station, which will have about 800 students, drawn from four schools that mostly serve the Brambleton area: Creighton’s Corner, Legacy, Rosa Lee Carter and Hillside. Roche has been an educator for 22 years, all with the Loudoun public school system. After starting her career as a fifth-grade teacher at Waterford Elementary in 1991, she taught at two middle schools before serving as assistant principal at Seldens Landing Elementary School for six years. For two years, she has served simultaneously as principal of two small elementary schools, Aldie and Middleburg.

The Washington Post recently spoke with both principals about the rewards and challenges of opening new schools.