Oswego City School District provides a three link tutorial on dilations. By clicking on each of these links, you will find the definition of a dilation, examples of dilations, and a quiz to test your skills.

This site offers a very basic discussion of dilations. It explains what a scaling factor is and provides illustrations.

To make sense of this, you have to first see the Twin Paradox: Introduction, which is the special relativity version and is linked to this page. This general relativity explanation views the paradox from a gravitational point of view.