A is for anticipation: Students lean forward, hands on meaning they are good to go. If you see this state in nearly all of your students, they are ready for the next step: the trigger word
B is for backing off: Apathetic signs include leaning back in their chairs and rolling their eyes meaning they are not buying into what you're asking them to do. Increase their buy-in by improving your framing of the event. Give them a better reason to do what you're asking them to do
C is for confusion: They look side to side for help from peers, and their fore heads may be wrinkled-meaning they don't understand what you're asking them to do. Offer directions again, and either simplify them, review them, or say them differently.
Finally we get to the sixth and last of our direction-giving steps. Give th trigger word you introduced earlier. Be consistent with it, and s it with enthusiasm, with your hands matching the nonverbal communications, "Ready, go!