Abstract
This study aimed to develop interactive multimedia based on the Concrete-Pictorial-Abstract (CPA) approach and determine its validity, practicality, and effectiveness in improving the self-efficacy of elementary school students in learning plane geometry. This research employed a Research and Development (R&D) method using the ADDIE model, consisting of analysis, design, development, implementation, and evaluation. The subjects were 55 students at SDS IT Asy-Syakur, comprising 29 students in the control group and 26 students in the experimental group. Data were collected through observation, interviews, expert validation sheets, response questionnaires, and self-efficacy questionnaires. The results showed that the interactive multimedia obtained validation scores of 96% from media experts, 98% from language experts, and 100% from material experts, all categorized as highly valid. Teacher responses reached 81.67%, while student responses reached 85.68%, indicating high practicality. Self-efficacy scores in the experimental group increased from 68.13 to 80.19, with an N-Gain score of 0.38, while the control group increased from 66.81 to 71.30, with an N-Gain score of 0.14. The hypothesis test produced a significance value of 0.000 (p < 0.05), indicating a significant difference between groups. Thus, the CPA-based multimedia was valid, practical, and effective in improving students’ self-efficacy in plane geometry learning.