C.J.

C.J. is a genius and a student of the River City local school Public School 201.

Characteristics
C.J. wears a striped turquoise hoodie with dark blue pants and has dreadlocks with green and yellow beads on them.

She is described as being a very smart student, having won all of Mr. Silva's science fairs. She is presumably in elementary school, based on the naming of her school as P.S. 201 or Public School 201, which is usually used to refer to primary schools in New York.

Role on Shrink Ray Island
C.J. was one of Mr. Silva's students, and she won every science fair he ever held at the school. She became very popular and Mr. Silva realized he could get that kind of popularity (and money) if he stole one of her inventions. So he swiped the Shrink Ray she was planning on unveiling at the science fair and used it to shrink her down and kept her in his office to keep her quiet. She was able to contact a Poptropican who had also been shrunk through morse code and a telescope. She told the Poptropican that Mr. Silva was the thief. The Poptropican rushed to go find her, but Mr. Silva tried to shrink them down to an impossibly small size, which would probably destroy them. But the shrink ray bounced off of a mirror and hit him, which shrunk him down and caused him to fall into a jar of ants. The Poptropican and CJ reversed the gun and shot themselves to return to normal size and CJ used Mr. Silva as her science fair project, "The Incredible Shrunken Man."

Trivia

 * She was mentioned to have won three other science fairs.