 While there have been a few characters from varying grades have been depicted in recurring minor roles, the students in the fourth grade—including central characters Stan Marsh, Kyle Broflovski, Kenny McCormick, and Eric Cartman—receive the primary focus of the series.The fourth grade class is taught throughout most of the series by Mr. Garrison, with a hiatus between seasons 4 and 6 when he is replaced by Ms. Choksondik.These students also attended class under Mr. Garrison during their previous time as third graders during "South Park"s first three-and-a-half seasons.