The National Council of Teachers of Mathematics (NCTM, 1989, 2000) and the new "Australian Curriculum: Mathematics" for senior secondary (ACARA, 2010) highlight the importance of teaching spatial reasoning as early as preschool when mathematics is introduced. Studies have shown that there is a relationship between spatial abilities and mathematical achievement (Burnett, Lane, & Dratt, 1979; Casey, Nuttall, Pezaris, & Benbow, 1995; Geary, Saults, Liu, & Hoard, 2000). Activities that enhance spatial reasoning skills are invaluable to, and should be encouraged in, classroom instruction. Casey, Andrews, Schindler, Kersh, Samper, and Copley (2008) define spatial skills as "the ability to think and reason through the comparison, manipulation, and transformation of mental pictures" (p. 270). In this article, the author presents an activity (Aichele & Wolfe, 2007, p. 11) to pre-service high school teachers. Though the activity seems simple, it can be challenging to students who have not been exposed to spatial tasks. The activity goal is to create a square from a given polygon by making one straight cut so that two pieces, when put together without overlap or gaps, form a square.