Enhancing Students' van Hiele Geometric Thinking Levels Through the Integration of Geometer's Sketchpad (GSP) in Geometry Learning

Van Hiele’s theory of geometric thinking describes a hierarchical progression through distinct levels, from basic visualization to advanced deductive reasoning. Students typically struggle to transition between these levels without appropriate instructional support. Dynamic geometry software, such as Geometer’s Sketchpad (GSP), has been shown to facilitate this transition by providing interactive visualizations and exploratory learning experiences. By allowing students to manipulate geometric shapes and observe properties dynamically, GSP enhances conceptual understanding and promotes higher-order thinking. This study aims to analyze the development of students' geometric thinking levels on geometry topics based on Van Hiele's theory after instruction using Geometer's Sketchpad (GSP). The research employed a qualitative approach, involving three participants from Class VIIG of a junior high school in Mojokerto, Indonesia, representing high, medium, and low ability levels. Data were collected through a test consisting of three questions designed to assess students' geometric understanding across various indicators of Van Hiele's thinking levels, followed by in-depth interviews. The findings revealed that GSP-based learning was effective in enhancing students' geometric thinking. Subjects ST and SD demonstrated significant progress, with several indicators advancing from Level 0 (Visualization) to Level 2 (Informal Deduction). In contrast, subject SR exhibited limited improvement, with most indicators remaining at Level 1 (Analysis). These results highlight GSP's potential to support students in developing a deeper understanding of geometric concepts. This study provides valuable insights for designing learning strategies tailored to the diverse needs and abilities of students, aiming to facilitate higher levels of geometric thinking.