Congruent Angles: Definition

The following applet illustrates what it means for two angles to be classified as congruent angles. Interact with this applet for a few minutes, then answer the questions that follow. Be sure to move the BIG PINK POINTS around each time before you re-slide the slider.
Questions: 1) What geometric transformation(s) took place in the applet above? List it/them. 2) Did any of these transformations change the measure of the original green angle? 3) Cause: How would you define what it means for angles to be congruent with respect to the geometric transformations you listed in (1) above? 4) Effect: If we know that two angles are congruent, what can we consequently conclude about their measures?