Simplify the following text for a Grade 6 native English-speaking person.
Original: John Christian Watson ( 9 April 1867-18 November 1941 ) , commonly known as Chris Watson , Australian politician , was the third Prime Minister of Australia .
Simplified: John Christian Watson ( c. 9 April 1867 - 18 November 1941 ) , known as Chris Waston , was the third Prime Minister of Australia .