How do I loop through all of my children, and display each? I would like to know the best way to do this.

my children and container
five children, one plays every sec, 1,2,3, etc.

 var square1:Square1 = new Square1;
 var square2:Square2 = new Square2;
 var square3:Square3 = new Square3;
 var square4:Square4 = new Square4;
 var square5:Square5 = new Square5;

 var container:Sprite = new Sprite;
 addChild(container);
 container.addChild(square1)
 container.addChild(square2)
 container.addChild(square3)
 container.addChild(square4)
 container.addChild(square5)

my timer

 var timly:Timer = new Timer(1000, 5);   
  timly.start();
  timly.addEventListener(TimerEvent.TIMER, onLoop);

Note:
Tried for loop, numChildren -1, and visibility

ERROR 'access of undefined property'

//Thomas's idea

    var timly:Timer = new Timer(1000, 10);          
        timly.start();
        timly.addEventListener(TimerEvent.TIMER, onLoop, false, 0, true);
//      
    var square1:Square1 = new Square1;
            square1.visible = false
            container.addChild(square2)
    var square2:Square2 = new Square2;
            square2.visible = false
            container.addChild(square3)
    var square3:Square3 = new Square3;
            square3.visible = false
            container.addChild(square3)
    var square4:Square4 = new Square4;
            square4.visible = false
            container.addChild(square4)
    var square5:Square5 = new Square5;
            square5.visible = false
            container.addChild(square5)
    var container:Sprite = new Sprite;
            this.addChild(container);

    var curCount:Number = 100;
//
function collectChildren(container:DisplayObjectContainer):Array {
     var len:int = container.numChildren;
     var mySquaresArray:Array = [];
     for (var i:int = 0; i < len; i++) 
     {
          mySquaresArray.push(container.getChildAt(i).name);
     }
     return mySquaresArray;
}
//
function onLoop( e:Event )
{
    curCount = e.target.currentCount;
    if( curCount > 1 ) {
        var previous_square = curCount -2;
        mySquaresArray[previous_square].visible = false;
    }
    var current_square = curCount - 1;
    mySquaresArray[current_square].visible = true;
}