\input zb-basic \input zb-matheduc \iteman{ZMATH 2016c.00941} \itemau{Hodgson, Theodore; Schultz, David} \itemti{A refreshingly rational approach to the center of mass.} \itemso{Math. Teach. (Reston) 108, No. 9, 710-715 (2015).} \itemab From the text: In this article, we present a cross-curricular modeling activity that brings rational functions to life. The activity, which connects rational functions with concepts from elementary physics, illustrates the beautiful and often surprising connections between mathematics and the world of students' experience. Issues related to the center of mass (the balance point) arise in everyday situations and are often of critical importance. For instance, the contents of an airplane must be positioned to maintain the overall balance of the plane; towers and silos are constructed to be steady and stable (achieved through a low center of mass in relation to the entire structure); and even athletic success and the development of motor skills are linked to an ability to control one's center of mass. \itemrv{~} \itemcc{M50 I20} \itemut{rational functions; mathematical applications; physics; student activities; soda can problem; center of mass; mathematical model building; proportion; extreme values; approximation} \itemli{http://www.nctm.org/Publications/Mathematics-Teacher/2015/Vol108/Issue9/A-Refreshingly-Rational-Approach-to-the-Center-of-Mass/} \end