This study developed a learning system that allows teachers to edit assignments designed to teach students the text structure strategy through the use of four phases: instructing, modeling, practicing, and reflecting. A 7-week instructional experiment was conducted in which 84 12th-grade students learned the text structure strategy using this system. The results produced several significant findings. First, the students demonstrated very different patterns of accessing time when using this system, making it possible to classify them into 3 categories or clusters of users: "low-practice-low-reflection students", who spent little time using the system; "low-practice-high-reflection students" who spent most of their time in the reflecting phase, during which they constructed graphic organizers and wrote summaries primarily by referring to the teacher's examples; and "high-practice-low-reflection students" who spent most of their time in the practicing phase, during which they constructed graphic organizers and wrote summaries without referring to the teacher's examples. Second, the students' patterns of accessing time were related to their prior knowledge, Web experience, and learning performance. In particular, the "low-practice-low-reflection students" had the lowest learning performance. The "low-practice-high-reflection students" had a higher frequency of using PCs to access the Web, a lower level of prior knowledge, and higher gain scores than the "high-practice-low-reflection students". These findings are discussed, and several suggestions are proposed for future research work.