Simplify the following text for a Grade 14 native English-speaking person.
Original: A number of classification schemes are currently in existence ( 2 ) ( 3 ) , and while they strive to retain some mutual consistency , quite a few asteroids are sorted into different classes depending on the particular scheme .
Simplified: A number of classification schemes are currently in existence , and while they strive to retain some mutual consistency , quite a few asteroids are sorted into different classes depending on the particular scheme .