Rotating Produces Odd Results [Unity 2D]

I've been working on a rhythm game in unity 2d, and I found something odd: Rotating an objects z-axis to the value of 1 makes it 90 degrees, -1 to -90 degrees, and anything else to 180 degrees. Hm?

 #pragma strict
 var arrow : Transform;
 var pos = new Array();
 var rotation = new Array();
 
 function Start()
  {
  pos = [-0.9, -0.3, 0.3, 0.9];
  rotation = [1, 180, 0, -1];
  var direction;
 
  for(var i = 0; i <= 16; i++)
   {
   direction = Random.Range(0, 4);
   var clone = Instantiate(arrow, Vector3(pos[direction], -2.4, 0), transform.rotation);
   clone.transform.rotation.z = rotation[direction];
   Debug.Log(rotation[direction]);
   yield WaitForSeconds(1);
   }
  }