1971 with enrollment rising, Appleby was split into a Junior and Senior School. Junior School consisted of grades 4 through 8. Previously the school had admitted boys as young as grade 1. Senior School consisted of grades 9 through 13. In 1973, Appleby introduced the innovative Northward Bound outdoor education program at the school's "Northern Campus" on Rabbitnose Island, Lake Temagami. In 1976, participation in the Senior School Cadet Corps became optional for students in grades 11 through 13. In 1984, it became a completely voluntary corps. Appleby maintained #440 Royal Canadian Army Cadet Corps for 93 years, until 2008, and it was open to both boys and girls. In 1979, the school cook, Hilda Chattaway, reached a remarkable milestone of 50 years of continuous service to Appleby. She continued to run the school's kitchen until her death in 1985. In 1982 the Junior School boarding dormitory located on the top floor of Colley House was named after her. However, boarding for the Junior grades was discontinued in 1990. September 1980 marked the first time day students outnumbered boarders Appleby commemorated its 75th anniversary during the 1985–1986 school year. Memorable events from that year included the first football team's undefeated season and first and only CISAA championship, and the visit of Lady Mountbatten to officially open the new wing to the classroom building. The new facility was called Nicholas Court and housed facilities for art, music and debating, in addition to new classrooms. Appleby was one of the first high schools in Ontario to eliminate Grade 13, moving to a four-year program with a "double cohort" graduating class in 1987. All high schools in Ontario moved from a five-year to a four-year program . In 1990, Saturday classes were eliminated. Previously, a chapel service and classes were held on Saturday mornings and sports were played in the afternoon. Up until the 1970s, boarders had also attended a Sunday church service at St. Jude's Anglican Church in Oakville. Prior to becoming co-educational in 1991, Appleby was a school for boys only. Girls were admitted in grades 6 to 11. Before then, Appleby's sister school was St. Mildred's-Lightbourn School, an Oakville private school for girls. Appleby and St. Mildred's often collaborated in drama, for example. At the same time that girls were admitted, grades 4 through 6 were phased out and the Junior School/ Senior School division was eliminated. Michael Nightingale was