Algebra students typically pay little attention to choosing appropriate domains, ranges and scales of axes for graphing functions. The purpose of this study was to investigate the effect of introducing an assignment and employing the graphing calculator to examine and alleviate students' difficulties regarding the selection of appropriate domains, ranges and scales of axes for graphing functions and to examine difficulty students might have regarding the identification, construction and definition of function. The research sample consisted of 128 college algebra students enrolled in a north-central Florida community college. There were eight classes of students: six treatment classes and two control classes. All classes were intact, thus random assignment of students to the classes was not possible. Two classes were in each of the following groups: Graphing Calculator and Assignment Group, Graphing Calculator Only Group, Assignment Only Group, and the Control Group. The analysis of covariance was used to examine mean differences on two instruments between the four groups in the study. The Domain/Range/Scale Instrument and the Identification/Construction/Definition Instrument were both administered as pretests and posttests. The results of the study suggest that the treatments were in various ways interactively and independently effective regarding the students' understanding of the concept of function. Contains 25 references. (Author/MKR)