<![CDATA[The development of the Nusantara Capital City (IKN) has triggered social and educational transformation in East Kalimantan, requiring teachers to implement adaptive, contextual, and learner-centered instruction. Differentiated instruction allows teachers to adapt content, processes, and products based on students’ readiness, interests, and learning profiles. Consistent with Universal Design for Learning, these adjustments promote active learning and deeper conceptual understanding. Therefore, differentiated instruction is viewed as an approach that supports deep learning, emphasizing meaningful understanding, critical thinking, knowledge transfer, and reflection. This study explored junior high school teachers’ lived experiences and interpretations of implementing differentiated instruction to support deep learning in the IKN buffer areas of East Kalimantan. Using a qualitative phenomenological design, the study was conducted in junior high schools in Samarinda, Balikpapan, and Penajam Paser Utara. Fourteen teachers who were implementing the Merdeka Curriculum and differentiated instruction were selected through purposive sampling. Data were collected through interviews, observations, and documentation, and analyzed using Colaizzi’s phenomenological method. The findings identified three main themes: (1) pedagogical adaptation through adjustments to content, processes, and products; (2) contextualization of deep learning through integrating IKN-related issues into meaningful mathematics learning; and (3) implementation challenges, including limited facilities, administrative burdens, diverse student abilities, and teacher competency development. The findings suggest that differentiated instruction supports deep learning by aligning instruction with students’ readiness and authentic learning contexts. This study contributes to the literature by connecting differentiated instruction, deep learning, and IKN-based contextual mathematics learning, while providing practical insights for teachers and schools to design inclusive, meaningful learning environments.]]>
