clay class
Are you one of the 'special' children? Does your teacher keep a spare set of clothes for you in the cupboard? Do the other kids tease you? Does playing with, and occasionally eating, clay feature very prominently in your education? Then you're either in, or about to end up in, the clay class.
'Stevie's in the clay class. Lucky sods, they just eat clay and drool all day'
Clay Class
The class that probably plays with clay all day in class and doesn't do any work since they are 'special'. Hence the name "Clay Class"
"Haha, Jacob just shit himself!"
"Isn't that the kid from the clay class?"
"Isn't that the kid from the clay class?"