A well-known lesson taught by many upper-elementary and early-middle-school teachers at the beginning of the school year asks students to compare how arm span relates to height. Students measure their height and arm span and compare their measurements to those of their classmates. This lesson gets students measuring, graphing, and practicing important science skills, and it can be used to build the necessary foundation to discuss science concepts such as variation within a population. Here the author presents how he has taught this lesson and discusses how to incorporate mathematical standards from the Common Core State Standards for Mathematics (CCSSM) (CCSSO and NGA 2010) and scientific practices from the new "Framework for Science Education" (NRC 2012). (Contains 2 figures.)