This "quick tutorial" introduces the general idea of a call and explains the most common cases. It does not explain or illustrate all cases. For additional details and/or examples, refer to the links in the "MORE INFO" box.
If the dancers don't do the 1 and 1/2 Circulates precisely, in sync, they sometimes have trouble knowing whose hand to take. Being aware of how this call works from each of the four positions of the initial column can be very helpful in avoiding problems.
The second dancer in the original column ("#2") doesn't have to worry about who to meet. The 1 and 1/2 Circulates will bring that dancer to the very end spot, not holding hands with anybody.
As the #3 and #4 dancers walk forward, they will be passing people walking in the other direction, and so they will find themselves passing by two other people before they meet the person with whom they should take hands. (You may hear dancers chanting something like "No, No, Yes", as a reminder of this.)
The #4 dancers have an advantage -- it is very easy for them to see the person that they are going to meet. It is the other #4 dancer, in the diagonally opposite corner of the square. If these dancers make eye contact with each other, and both just walk forward and take hands in the very middle of the square, they can be sure they are in the right place -- and this can help clear up any uncertainty there may be in the minds of the dancers immediately in front or behind them.
After the 1 and 1/2 Circulates, the six dancers who are holding hands Trade.
Finally, the two dancers in the very center and the two at the very end "move up" to become the ends of lines. The other four (the ones who traded but are not in the very center) are done. They just wait for somebody to move up next to them.
Note that, as they "move up", the dancers coming from the very center do not turn. But the dancers from the very end positions must turn 1/4 (90 degrees) to have the correct facing direction.