Sister Mary Margaret Duffy, 100, is celebrating her 85th year as a member of the Dominican Sisters of Amityville, L.I. She entered the congregation in 1929 from Our Lady of the Miraculous Medal parish, Ridgewood.  She received the religious name Sister Mary Arthur.

From 1930 to 1943, she taught at All Saints Elementary School, Williamsburg, and St. Elizabeth, Ozone Park. From 1943 to 1963, she was at Dominican Commercial H.S., Jamaica.

After studies at Catholic University in Puerto Rico, she taught at Molloy College, Rockville Centre, L.I., 1969-79.