Graphic scores, which use symbols, letters, and pictorial forms instead of traditional staff notation, offer unique opportunities for creative musical expression in education. While staff notation emphasizes reproducibility and Western musical conventions, graphic scores allow performers to interpret visual representations, fostering inventive and individualized engagement. This study situates itself within the growing pedagogical interest in improvisation and personalized composition, as highlighted in the Course of Study for Elementary Schools (MEXT, 2017), and builds on prior research demonstrating the social and expressive benefits of graphic score activities.The aim of this study was to elucidate how students generate musical ideas from visual images in their graphic scores, and to identify the forms of musical expression that emerge through this process. Specifically, the research focused on individual creative behavior, examining how interpretation itself can function as a compositional act.The study involved 25 members of the chorus club at Kanazawa University Junior High School. Each participant created an original graphic score on A3 paper and performed it using instruments including a glockenspiel and a custom digital interface. Performances were video-recorded for behavioral analysis, and participants completed questionnaires assessing expressiveness, concentration, enjoyment, instrument control, stimulation, and overall satisfaction. Behavioral patterns such as tone selection, repetition, exploration of new ideas, and silence were coded and analyzed to understand the relationship between visual representation and musical output.Results indicated that students actively engaged in selecting and repeating tones, exploring novel ideas, and experimenting with expressive nuances. While some performances covered only portions of the graphic scores, nearly all participants produced distinctive musical moments corresponding to their visual designs. The integration of multi-track recording and digital instruments was found to have potential for enabling fuller realization of imagined musical ideas, complementing the expressive capabilities of acoustic instruments.These findings suggest that graphic scores, combined with both traditional and digital instruments, can enhance creative expression and support individualized learning in music education. They emphasize the importance of fostering environments where students can experiment, interpret, and reflect, highlighting pedagogical strategies that balance technological tools with conventional instruments. Ultimately, the study contributes to understanding how visual and technological approaches can cultivate musical imagination, expressiveness, and sensitivity, providing practical implications for music educators seeking to expand the creative potential of their students.