Studies have shown that students' understanding is typically analytic and not visual. Two possible reasons for this are when the analytic mode, instead of the graphic mode, is most frequently used in instruction or, when students or teachers hold the belief that mathematics consists simply of skillful manipulation of symbols and numbers. The National Council of Teachers of Mathematics (NCTM) states that: "Different representations support different ways of thinking about and manipulating mathematical objects. An object can be better understood when viewed through multiple lenses" (2000, p. 360). This article presents two ways of visualising a series in "proof without words" (PWW) style (Nelsen, 1993; 2000). The contention is not that one representation is superior to another, only that students often construct vastly different personal and idiosyncratic representations which lead to different understandings of a concept. (Contains 9 figures.)