Potter was born in Bemidji, Minnesota, a curling hotbed. She began playing the game at age 5, and honed the strategic elements of her game by watching Canadian curling competitions on television. After playing as an alternate at the 1998 World Junior Curling Championships for the 5th-place U. S. team skipped (captained) by Hope Schmitt, Cassandra returned to the Junior Championships in 2002, this time as the skip of the team; she and her United States squad went on to capture the gold medal with a win over Matilda Mattsson of Sweden. In 2003, Cassie returned once again to the World Junior Championships, and once again made it to the final. However, this time she lost, with Marliese Miller of Canada winning the gold.