Initial setup is to line up in line with the disc, as if you're starting a foot race with your teammates. Among the 3 in the race, you call a number, which corresponds to the person who will be cutting back. 2 will be #0, 3 will be #1 and 4 will be #2. In this example, #1 is called so 3 will be the one cutting back.
Go for a race! 2 is cutting more at a diagonal and is being aware that they may get an IO throw.
3 cuts back for an open under.
And then we can run a box, or just look for continuations. This shows running a box.