Simplify the following text for a Grade 10 native English-speaking person.
Original: In 2002 , filmmaker Michael Moore released a documentary movie called Bowling for Columbine that was about why the shooting happened and about the role guns have in American culture .
Simplified: In 2002 , Manson appeared in Michael Moore 's documentary Bowling for Columbine during the band 's first show in Denver since the shooting .