This study developed and preliminarily evaluated Treffinger digital teaching materials integrating Ethno-Science, Technology, Engineering, Arts, and Mathematics (Ethno-STEAM) for fourth-grade Integrated Natural and Social Sciences (IPAS) learning. The study addressed students’ limited experience in solving contextual science problems and the underuse of local cultural resources as meaningful learning contexts. An educational design research approach adapted from Plomp’s model was implemented through preliminary research, prototyping, and assessment phases. The preliminary phase involved 126 fourth-grade students and classroom evidence from elementary schools in Malang Regency, Probolinggo City, and Blitar City, East Java, Indonesia. The prototyping phase produced a model guide, lesson modules, digital teaching materials, student worksheets, and assessment tools aligned with the Treffinger stages of Understanding the Challenge, Generating Ideas, and Preparing for Action. Two experts evaluated content and construct relevance, followed by a small-scale try-out with 11 students and field implementation involving complete paired data from 120 students and practicality ratings from three teachers. Expert review showed strong feasibility (87%; Aiken’s V = 0.84). Practicality was high in the small-scale try-out (teacher = 93%; students = 97%) and field implementation (teacher = 94%; student mean = 4.63/5 or 93%). Students’ mean scores increased from 69.47 to 88.65, with a moderate N-gain of 0.63. These findings provide preliminary evidence that the materials are feasible, practical, and potentially effective for supporting culturally situated creative problem-solving in elementary IPAS learning. However, the one-group pre-test–post-test design limits causal interpretation.