1.1: THE MOST COMMON CASEThe basic idea of counter rotate is that everybody in a formation moves a certain amount around a center point, while at the same time turning the same amount.
Most commonly, the amount to turn is 1/4 of a circle (90 degrees).
The illustration shows the dancers in a box turning 1/4 of the way around the center point of the box.
Everybody is moving in an arc 1/4 of the way along a small circle. Everybody is turning 1/4 (90 degrees, "one wall") at the same time.
Everybody who starts facing head walls is now facing side walls.
You may find it helpful to imagine the people standing on a turntable of some kind -- a merry-go-round, a phonograph turntable, or a lazy-susan -- and they are all moving together as that platform turns.