Simplify the following text for a Grade 5 native English-speaking person.
Original: While he gave his manuscript to his agent and editor to review , Riordan took his book to a group of 6th , 7th , and 8th graders to read and give their critique .
Simplified: He gave his manuscript to his agent and editor to review . At the same time , he gave the book to some sixth , seventh and eighth graders to read and tell him what was good or bad about it .