Zack taps his right pointer and middle fingers against his left palm, which translates to the command "Assemble." And all the kids assemble.
	Zack brings his right hand up at a right angle to his body, two fingers raised; the scene cuts but he likely brings it down again, which translates to the command "Head Count." We assume that he then does one to make sure everyone is assembled.
	Zack taps his fingers against the back of his left hand, which loosely translates to the command "It's Time" or "Time's Up."
	Zack cuts his fingers across his throat left to right, which translates to "Danger Area."
	Finally, Zack holds up two fingers, points to each pair (left) and sends them off in different directions (right). These are not specific commands but simply general directions to pair off and disperse.