“…Research suggests that undergraduate students are entering the university with weak understandings of functions, and entry level university courses do little to address this deficiency (Monk, 1992;Monk & Nemirovsky, 1994;Thompson, 1994a;Carlson, 1998). Recent investigations of college students' understandings of functions have documented that even academically talented undergraduate students have difficulty modeling functional relationships of situations involving the rate of change of one variable as it continuously varies in a dependency relationship with another variable (Monk & Nemirovsky, 1994;Thompson, 1994a;Carlson, 1998). Research has also shown that this ability is essential for interpreting models of dynamic events (Kaput, 1994;Rasmussen, 2000) and is foundational for understanding major concepts of calculus (Kaput, 1994;Thompson, 1994a;Cottrill, 1996;Zandieh, 2000) and differential equations (Rasmussen, 2000).…”