BILLERICA -- Margaret I. Mason, lifelong resident of Billerica, died Thursday, March 15, at Lahey Clinic Medical Center in Burlington. She was 89.She was born in Lowell, Jan. 17, 1918, daughter of the late Melvin and Ella (Wyers) Mason. She graduated from Howe High School in Billerica, and Lowell State Teachers College.Miss Mason was a teacher for 36 years at the Parker and Kennedy Elementary Schools in Billerica.She is survived by a brother and sister-in-law, Melvin and Barbara Mason of Stanwood, Wash.; her nieces and nephews, Allan Mason of Arlington, Wash., Nancy Mason of Federal Way, Wash., Carol Shaffer of Stanwood, Wash., Richard Crocker and his wife, Lee of Mashpee, David Crocker and his wife Pamela Nishball of Ashford, Conn., Brian Crocker and his wife, Linda of Marion, N.Y., David Mason, Jr. and his wife, Ann Marie Mason of Atkinson, N.H., and Robert Mason and his wife, Doreen of Lowell.She is also survived by 16 grandnieces and grandnephews; and several great-grandnieces and great-grandnephews.She was also the sister of the late Barbara Crocker and David Mason.