["Journal of Computer Assisted Learning, Volume 42, Issue 3, June 2026. ", "\nABSTRACT\n\nBackground\nPre‐service mathematics teachers frequently struggle with understanding the definitions and hierarchical classifications of quadrilaterals, often misidentifying inclusive relationships. These misconceptions hinder their ability to teach geometry effectively and reflect gaps in both content knowledge and pedagogical readiness. While collaborative digital tools like wikis have demonstrated potential for fostering reflective and dialogic learning, their application in mathematics teacher education remains limited and underexplored.\n\n\nObjectives\nThis study aimed to investigate how a wiki‐based collaborative learning environment could enhance pre‐service teachers' conceptual understanding of quadrilaterals and inform the development of evidence‐based instructional design principles.\n\n\nMethods\nThis study adopted a three‐phase Design‐Based Research (DBR) methodology, comprising a pilot study and two iterative cycles, with 31 pre‐service mathematics teachers participating (4 pilot, 8 Iteration 1, 19 Iteration 2). The intervention used a Moodle‐based wiki in which participants collaboratively defined six quadrilaterals and determined instructional sequencing. Each phase involved designing wiki scaffolds, implementing the task, and analysing weekly wiki logs and interaction patterns to inform iterative refinements to task structure and scaffolding. Improvements were made on task design and scaffolding strategies between cycles considering wiki content analysis.\n\n\nResults and Conclusions\nFindings indicate that wiki‐supported collaboration progressively enhanced participants' definitional precision, engagement in hierarchical reasoning, and pedagogical content knowledge. Over time, learners shifted from exclusive to inclusive definitions, demonstrating advancement along van Hiele levels of geometric thinking. Despite persistent challenges such as uneven participation and limited multimodal representation, the study confirms the potential of wikis as social constructivist tools in teacher education and contributes practical design principles for integrating collaborative technologies into mathematics instruction.\n\n"]