Did you know??
*The origins of contra dancing go back to colonial days, and its roots can be traced to English country dance. It’s really a group rather than a couples effort, and it has elements that might remind you of traditional square dancing. Rhythm and pattern are the keys.
*The music for contra dancing is highly structured. Everything occurs in units of four. The band plays a tune for 16 beats, repeats the tune, then plays a new tune for 16 beats and repeats that. An eight-beat section is known as a call, during which each block of four dancers executes a called-out instruction. An entire dance is precisely 64 beats long.

So here's how it goes:
*When the dancers line up in their groups of four to make a long column down the floor extending away from the band, each square block consisting of two couples is like a matrix. Each dancer is in a specific position within the matrix. The called instructions correspond to movements of the elements of the matrix. After 64 beats, however, the first and second rows of the matrix must be interchanged.
They'll look like this...