The accompanying text lacks clarity. Consider, for example, the first two sentences:
"One of the peculiar aspects of Einstein's theory of special relativity is that the length of objects moving at relativistic speeds undergo a contraction along the dimension of motion."
What special relativity predicts is that an observer moving relative to the object measures a shorter length along the direction of motion.
"An observer at rest (relative to the moving object) would observe the moving object to be shorter in length."
An observer at rest relative to the moving object measures the proper length of the object. The later part of this text provides more of the necessary emphasis on measurement.
Quantitative results are given, but no details of the theory.