Simplify the following text for a Grade 6 native English-speaking person.
Original: His four younger sons are distinguished from one another by the nicknames `` Monk '' , `` Big Wheel '' , `` Red '' , and `` Little Joey '' .
Simplified: They are also known by the nicknames `` Monk '' , `` Red '' , `` Joe '' `` Big Wheel '' and `` Little George '' .