The Pencak Silat class is Jim's class for teaching Kadic Academy students the art of Pencak Silat. It is held in the Gym, as it is essentially the equivalent of a dojo. Two main students are Yumi and Ulrich. Three secondary students, shown only in Canine Conundrum, are Sissi, Johnny, and Hiroki, with no others attending. According to Sissi, the classes are open to anyone and everyone except for the younger students (as Milly and Tamiya came in uninvited). This class was originally hinted in XANA Awakens as well. However, the only two students who appeared at the time were Ulrich and Yumi and it only appeared to last around a total of 5 minutes.
As stated above, Jim is the sensei in these classes. He even told Sissi that "only serenity will lead you to calmness". This is ironic considering that Jim is known for his fits of anger and his tendency to yell at the children.