Simplify the following text for a Grade 5 native English-speaking person.
Original: In the mid 1950s , Vonnegut worked very briefly for Sports Illustrated magazine , where he was assigned to write a piece on a racehorse that had jumped a fence and attempted to run away .
Simplified: In the mid 1950s , Vonnegut worked for Sports Illustrated magazine for a very short time . He was asked to write about a racehorse that had jumped a fence and tried to run away .