=344.= The first collective instruction will, therefore, be in conforming to the march of a leader, thus confirming and extending the instruction given in the =School of the Trooper= (pars. 295, 298); _and reasonable proficiency in this instruction must be secured before any attempt is made to utilize either commands or signals in the execution of collective movements_, except, as prescribed in par. 363. =345.= It is difficult for a leader to lead the squad properly and at the same time to supervise the march and correct the errors of individual troopers. For this reason it is desirable, especially in the earlier collective drills, that the instructor have as an assistant another noncommissioned officer or a well-instructed trooper. The instructor then leads the squad and requires his assistant (who takes the positions best adapted for the purpose in view) to supervise closely the movements of the troopers and to correct errors by means of cautions _addressed quietly by name to the individual man or men concerned_. Later the instructor similarly supervises the execution of the march while requiring his assistant to lead the squad. As the troopers advance in the instruction the instructor should give each of them such practice in leading the squad as the progress of the individual trooper concerned may appear to justify. =346.= When instruction in leading (par. 367) has advanced to the point where the guide can preserve his proper distance from the leader and conform promptly and smoothly to the latter's movements, the other troopers meantime preserving their interval and alignment without undue constraint or unnecessarily abrupt changes of gait or pace, the instruction is extended progressively to include, in accordance with the methods prescribed in par. 347, the execution of the movements prescribed for the squad. =347.= Throughout the instruction prescribed by par. 346 the squad will continue as before to be _led_. In teaching each new movement the example and movements of the instructor as leader will be supplemented at first by oral commands only, then by oral commands accompanied by the corresponding arm signals for those movements for which such signals are provided (_see_ Signals, pars. 988-996), then by signals alone. _The commands and signals will be given by the actual leader._ When the instructor is not actually leading (par. 345) he may either indicate to the leader the movements to be executed or else leave to him the selection of such movements. =348.= After the oral commands and arm signals are thoroughly understood the instructor will practice the squad in passing from one formation to another, using oral commands for some movements, signals for some, and causing some (e.g., changes of direction) to be executed by conforming to the movements of the leader without the additional indication of either oral commands or signals.