Please answer the following question: Middlesex School is a co-educational non-sectarian day and boarding independent secondary school for grades 9-12 located in Concord Massachusetts. It was founded as an all-boys school in 1901 by a Roxbury Latin School alumnus Frederick Winsor who headed the school until 1937. Middlesex began admitting girls in 1974. The school is a member of the prestigious Independent School League and is one of five schools collectively known as St. Grottlesex. Given a list of categories: company, educational institution, artist, athlete, office holder, mean of transportation, building, natural place, village, animal, plant, album, film or written work, what category does the paragraph belong to?
Answer:
Educational Institution