Irish set dance Church in the form of the Public Dance Halls Act 1935. The rise of rock and roll in the 1950s caused the popularity of set dancing to fade. However, in the 1980s a revival started and many sets that have not been done for forty years or more are being recovered and danced again. To start, four couples are arranged in the form of a square to dance with each couple being in the middle of the sides of the square. Both the eight dancers in the group and the dance itself are called a "set". The dance is a
Challenge square dance And Left Thru", or notably, "Circulate"). However, Challenge demands that the dancers have precise understanding of the call definitions, and combines and modifies calls in a way that yields more complex interpretations. In addition to the calls which denote a particular dance action, Challenge dancing makes extensive use of "concepts" which denote modifications to calls – either how they are executed or to whom they apply. There are only a few concepts before C1, e.g., the "As Couples" concept in Advanced. Each Challenge level adds about another ten new concepts. As with calls, the number of concepts at C4 is