Fifth and Sixth Graders' Club

The Fifth and Sixth Graders' Club was a club exclusively open only to Fifth and Sixth Grade students (with exceptions given in special circumstances) in 98th Street School, which is accessed through a secret passage under the Queen's Jungle Gym, which only the Queen knows the access code to.

History
C.J. and the gang were first introduced to the club after C.J.'s successful protest against certain new school policies. Eventually, the gang gets a bit sick of it - with the exception Mickey and Rus that is. They begin to make fun of the lower Grades behind their back, along with their so-called new friends, frequent antagonists of the game. C.J. and the rest of the gang (except Mickey and Rus) then bring in new First Graders, Harold, and Chubby, much to everyone's anger, except Mickey and Rus, who apologize and join with the rest of the gang and the First Graders. They are then saved from a harsh punishment from Queen Florence II by the old queen, Barb. Afterwards, the gang is banned from the club - as a renewed punishment, which they do not mind.

Trivia

 * Many of the former Fourth and Fifth Grade characters in the show are seen in the club.
 * Brinklow, who by now was Brinklow by Royal Decree, knew the access code to the club. This could have possibly been due to some members of the club wanting to come into school early, and Queen Florence II not wanting to come in on that time.
 * The club is accessed through a tic-tac-toe-like mechanism.
 * Harold and Chubby are the first First Graders to ever go into the club (whilst currently in the First Grade).
 * Rachel was banned from the club because she's a snitch.
 * In this part of the feature-length movie C.J. and Friends: Taking the Fifth Grade, this is the last time we see Queen Barb.