Hi there!
There are four different types of transformations:
-Reflections
-Translations
-Rotations
-Dilations
In a reflection, the shape is simply reflected across a line of reflection. It does not change size or shape, so therefore it is a congruence transformation.
In a translation, the shape is moved up, down, left, or right. It does not change size or shape, so therefore it is a congruence transformation.
In a rotation, the shape is rotated around a point of rotation. It does not change size or shape, so therefore it is a congruence transformation.
In a dilation, the shape is made larger or smaller by a scale factor. It does change size, so therefore it is not a congruence transformation.
The transformation that is not a congruence transformation is a DILATION.
Hope this helps!! :)
If there's anything else that I can help you with, please let me know!