Simplify the following text for a Grade 6 native English-speaking person.
Original: After the attack on Pearl Harbor , Jolson became the first star to entertain troops overseas during World War II , and again in 1950 became the first star to perform for G.I.s in Korea , doing 42 shows in 16 days .
Simplified: After the attack on Pearl Harbor , Jolson became the first star to entertain troops overseas during World War II . Again in 1950 became the first star to perform for GIs in Korea .