<![CDATA[General Background: Twenty-first-century education prioritizes collaboration and mutual cooperation as fundamental competencies for elementary school students. Specific Background: Lower-grade learners frequently demonstrate passive behaviors during group activities, heavily relying on active peers rather than participating equally and sharing responsibilities. Knowledge Gap: While the Contextual Teaching and Learning (CTL) approach has been extensively researched for upper elementary grades, its specific application using tangible environmental projects to build teamwork among early-grade students remains underexplored. Aims: This research investigates the application of a CTL model based on an ecological collage project to foster cooperative attitudes in second-grade students at SDN Barengkrajan 1. Results: Utilizing a pre-experimental one-group pretest-posttest design with 21 participants, the intervention yielded a statistically significant mean score progression from 54.43 to 58.14, accompanied by a moderate Cohen’s d effect size of 0.768. Novelty: The pedagogical intervention uniquely combines contextual learning with an ecological collage activity utilizing school waste, requiring young learners to directly practice role division, active coordination, and mutual assistance. Implications: Integrating tangible, environment-based group projects into the curriculum offers lower-grade educators a practical pedagogical alternative to build essential social interactions and collaborative character aligned with the Merdeka Curriculum. Highlights: Contextual teaching models successfully translate abstract cooperation concepts into tangible collaborative behaviors. Ecological collage projects facilitate active role division and peer coordination among young learners. Group-based environmental activities produce a significant positive shift in student social interaction scores. Keywords: Contextual Teaching And Learning, Mutual Cooperation, Ecological Collage, Project Based Learning, Elementary Education]]>
