The purpose of this paper was to study the function of introspection in art education and to encourage students of art high schools to think independently about their own artistic process, based on the assumption that introspection positively contributes to further artistic development. Within the school system or as part of art classes, there is a lack of encouragement for introspection through the study of one's own artwork. Students rarely have the opportunity to track the development of their thoughts, attitudes, and feelings due to numerous factors, the most significant being the curriculum and teaching approaches. Therefore, the aim of this research was to discover how to achieve authenticity in students' artistic expression in class. The research focused on the relationship between idea and form. The results aimed to answer the following research questions: How does the relationship between idea and form in students' artwork change as they develop? What constitutes authenticity in the expression of high school art students? How can one express their own personality through art? The chosen method was a three-step action research combined with a case study of individuals, during classes of Graphic Design, involving fourth-grade students from the School of Applied Arts and Design in Zagreb. In the first step, students compared their previous works created in class and they used them to create their own personal posters. The second step involved projecting their future artistic expression and creating sketches for a personal pictogram. In the third step, students created their personal pictograms based on analysis and newly acquired insights. At the end of each step, the students filled out the same reflexive questionnaire. Suitable data collection instruments included a personal reflective journal, observations and notes, students' works, and documentation of teaching materials. It was expected that each individual’s artwork would reveal at least one recurring pattern (theme/motif/belief/mode of creation or thinking) that persists and captivates them throughout their four years of artistic creation. The anticipated result was that students would find an appropriate form for the personal idea they wish to express. The benefit of this research lies in encouraging self-analysis and filtering students' authentic expressions to provide them with a tool for more sincere artistic expression. The results showed that, initially, the students focused on the technical quality of the works, but over time, they developed a deeper connection and a more introspective approach, moving to the expression of inner feelings. Furthermore, the authenticity of their work grew as they connected their feelings more deeply with their work and made their own decisions. They responded positively to peer evaluations, resulting in more diverse and authentic work, as well as a positive working atmosphere in the classroom, whereas self-evaluation proved to be challenging. Written forms of introspection helped them express the more vulnerable aspects of their feelings.