Simplify the following text for a Grade 10 native English-speaking person.
Original: Alexander Berkman ( November 21 1870 â `` June 28 1936 ) was a Russian-American writer and a leading member of the anarchist movement of the 19th and early 20th centuries .
Simplified: Alexander Berkman ( November 21 , 1870 â `` June 28 , 1936 ) was an anarchist known for his political activism and writing . He was a leading member of the anarchist movement in the early 20th century .