Role in the special
Karen and her friends first appear in their classroom when Professor Hinkle tries to entertain them, to no avail. The school bell then rings and the kids run outside for the snow.
After running outside for fun in the snow, Karen and her friends build a snowman and name him Frosty. Frosty is then brought to life by Professor Hinkle's hat, leading Karen and her friends to realize that the hat must be magic. When Hinkle takes the hat back, the kids try to convince Hinkle that they did see Frosty come to life, but he denies their claims. Hinkle's rabbit, Hocus Pocus, however, deserts Hinkle and quickly returns brings the hat back to the children. The kids are at first very happy to see their snowman all living, but it suddenly starts to get warm, which means Frosty is in danger of melting. Karen and her friends decide to take Frosty to the local railroad station where he can get on on a train to the North Pole. Frosty and the kids then parade down the streets to the railroad station, with people seeing Frosty in shock, and being stopped by Traffic Cop on the way.
After arriving at the railroad station, the kids find a train with a refrigerated box car in which Frosty can ride, since none of them have any money for train tickets. After Frosty, Karen and Hocus board the train car, the rest of the kids stay behind as they wave goodbye to Frosty, Karen and Hocus as the train leaves.
Karen's friends later appear again during the film's credits doing another parade on Frosty's return.
Despite their semi-prominent role in the original special, Karen and her friends oddly didn't reappear in the sequel, Frosty's Winter Wonderland; a completely different group of kids appeared in their place.