Trigger-based Animated Instruction is based on the concept of cognitive load theory and multimedia learning theory. Based on the Trigger-based Animated Instruction, instructors design teaching materials corresponded to classroom instructions, which contribute to guiding attention more easily; and help students take the initiative to search, select and organize information; reduce the burden on working memory as well as cognitive load; and enhance learning. This study adopted a quasi-experimental design by using the simple quadratic function graph of mathematics teaching material, to examine learning achievement and cognitive load cross two different instructions, i.e. the trigger-base animated instruction and the traditional methodology. The result of this study shows that adopting the trigger-based animated instruction significantly helps students learn more effectively, and reduces the cognitive load. Additionally, the effect was more pronounced for high-achieving students.