During the late 1950s, Dr. Phoebe Hall Knipling, the Supervisor of Secondary Science education for Arlington Public Schools (APS) started a summer science enrichment program that incorporated outdoor education for students. The program aimed to improve students’ environmental awareness by providing hands-on science experience in nature. During the 1960s, students visited various public and private lands in Northern Virginia, but it became apparent a permanent location for the program would improve the experience. Open land in Arlington County was diminishing fast due to the county’s soaring population, as well as increased urbanization and development.
In January 1967, Dr. Knipling located a 200-acre site in Fauquier County at the foothills of the Blue Ridge Mountains, but APS lacked the funds to purchase the land. In May 1967, Dr. Phoebe Knipling met with representatives of the Natural Sciences for Youth Foundation in Connecticut, who advocated community involvement to acquire the property. Dr. Knipling started, with the help of community representatives, including parents of APS students and five school staff members, the Arlington Outdoor Education Association (AOEA) as a volunteer-run nonprofit on July 3, 1967 to create an outdoor lab exclusively for APS student use. Mrs. Susan T. Baker became the first president. Others first involved included J. Fuller Groom, J. Frederick Abel, Shirley Jolkoviski, Harold Mack, Paul Nelson, Joseph Newlin, and Theodore Taylor. The group began accepting donations and organizing fundraisers to earn the funds necessary to purchase the land. On March 14, 1968, the group purchased the land from Mary Rose Striker, who agreed to sell the property for less than market value to the group. At Dr. Knipling’s suggestion, the land became known both as Tahl which translates into Wonderful Valley and as Floraunaretum, meaning "interaction of flora and fauna in an outdoor setting." APS students began to visit the land to observe the forces of nature firsthand and learn about ecosystems and biology, among other topics.
After Dr. Knipling retired in 1975, the AOEA board voted to rename the property the Phoebe Hall Knipling Outdoor Laboratory to honor her years of service to science education in Arlington County. The AOEA made the final mortgage payment for the property in November 1978, after a generous donation from Mr. Preston Carruthers. The Outdoor Lab, currently containing about 225 acres, features open fields, forests, wildlife, springs, a lake, as well as hiking trails, camping sites, a classroom, kitchen and dining facilities, observatory, and plant and animal identification areas. The land is reserved exclusively for APS student use. Though the lab is owned, maintained, and managed by the AOEA Board of Directors, APS creates and delivers all educational programs.