We present a series of historical discussions and tractable experiments that explore scale in math and science. In particular, we trace the historical debate over one of Legendre’s proposed proofs of Euclid’s fifth postulate in which he, amazingly, uses arguments of dimensional analysis to prove the existence of similar triangles—triangles of the same shape but different scale. Building off of an earlier discussion of scale in science by Galileo, we propose experiments that allow student to explore the role of scale in nature. The experiments are designed so that they can be accomplished as classroom activities in a GeT course as well as in high school classrooms.