This study aimed to investigate whether elementary school students have different reading strategies based on various levels of text-diagram integrative processing and whether these reading strategies remain consistent or change over a three-year period. The study followed 176 students from grades four to six and observed their eye movements while reading scientific texts. Data were collected once each year. Text-diagram integrative behavior was analyzed using various eye-movement indicators. The number of saccades between the text and diagram was evaluated, as well as the total fixation durations of the longest eye-fixation run that stayed within the paragraph and diagram regions and the remaining eye-fixation runs on the same regions. A separate K-means cluster analysis was conducted on two different text sets (one identical and the other different across grades) to identify three reading strategy patterns at each grade level. The results showed that those associated with integrative processing (i.e., the "integrative group") constituted a minority across grades (16-25% of students), followed closely by those focusing largely on the main text ("textual group") (17-28%). The latter group showed a strong motivation to read but failed to utilize the diagrams for knowledge construction. The majority of the students (52-67%) were categorized into the "shallow group," which showed a relative weakness in both integrative processing and intensive text reading. There was greater consistency in group assignments for individual students between the two text sets within a given year (63% on average) compared to across grade levels (30%), suggesting the instability of reading strategies over time. A growing trend in integrative processing toward higher grades was not observed.