Measurement and Geometry
A good way to think about congruence is to ask, 'How much information do I need to give someone about a figure if they are going to draw it?' For example, surveyors go to a lot of trouble taking careful measurements of a landscape. They must know that everything important about that landscape can be calculated from the measurements that they have taken.
In an analogous way, a certain minimum amount of information is needed to draw a particular triangle. We will develop the congruence tests for triangles as a solution to this question.