You cut identical strips of fabric - the length depends on the repeat of the design...
Now you have strips of fabric all alike and depending on the pattern you are using, you then stack these identical strips into a 'stack' - 4, 6, or 8 (elements)
you pin or baste these stacks so they don't move around, lining up the designs so that each one matches down through the pile...
Now you cut out your pieces - wedges, or diamonds, or squares, 4/6/8 at a time and each one makes one square...
so when they are sewn they made a kaleidoscope affect..
oh, I guess they call it that because you "stack" the fabric then "whack" out all the pieces at once... I guess