High School Precalculus Students' Understanding of Slope as Measure

Twenty‐two high school precalculus students were interviewed to examine their understanding of slope as measure. The students examined and discussed real‐world situations involving slope: physical situations involving slope as a measure of steepness and functional situations involving slope as a measure of rate of change. For the various physical situations, students measured steepness with angles instead of ratios. Overall, they demonstrated a better understanding of slope in functional situations, but many students had trouble interpreting slope as a measure of rate of change. Instruction should focus on helping students form connections and providing opportunities for students to communicate their understanding.