LOWELL - Mary E. (Harrington) Mitchell, 60, a resident of the Highlands section of Lowell, a schoolteacher in the city who previously taught in Chelmsford, died Sunday night, Nov. 24, at Brigham & Women's Hospital in Boston. She was the wife of John M. Mitchell, with whom she celebrated their 36th wedding anniversary on Aug. 6.She was born in Lowell on Feb. 15, 1942, daughter of the late John and Mary (Tucker) Harrington, She attended Sacred Heart Grammar School and graduated from Lowell's Keith Hall in 1959. She received a bachelor's degree in education at Lowell State Teacher College and a master's degree in education at Northeastern University in 1971. Mrs. Mitchell was a communicant of St. Margaret Church in Lowell and a member of the Blessed Virgin Sodality of her parish.She currently was teaching in the Lowell school system, serving as a tutor at the Robinson School. Previously, she taught in the Chelmsford school system.Mrs. Mitchell was the former treasurer for Friends of Lowell High School and for the Callery Park Little League. An avid gardener and reader, she was also a member of the Lowell Quilters. Besides her husband, she is survived by a daughter, Susan E. Hubert and her husband Richard of Hudson, Mass.; a son, Thomas J. Mitchell and his wife Jocelyn of Lowell; a granddaughter, Abigail R. Mitchell of Lowell; a brother. John C. Harrington, residing in Pennsylvania; and many nieces, nephews, cousins, aunts and uncles.