There are three main ways to measure distances without the use of high technology devices like a GPS system. The simplest and least accurate is by guessing. The next most accurate method is with the use of pacing. To measure the distances between two points walk between them and count the number of steps. You can then measure your stride and estimate the distance between the two points. Make sure to keep your stride consistent while doing the study. Finally the more accurate method is to use a tape measure to measure distances.
Check out an example of GPS HERE