Background: Deaf students need access to the language and representations through which mathematical ideas are taught and assessed. 
Objectives: This study identified barriers and learning needs among Grade 7 deaf students and translated them into preliminary specifications for adaptive hybrid mathematics instruction. 
Methods: The define phase of a development study at SLB Negeri Kota Metro, Indonesia, combined eight classroom observations with teacher questionnaires, learner profiles and diagnostic tasks, document analysis, and interviews with two teachers, four parents or guardians, and one health professional. The lead researcher coded interviews and observation notes and compared categories across sources. 
Results: Four needs emerged: visual and communication access, explicit links between concrete, pictorial, and symbolic representations, scaffolding adjusted to learner responses, and opportunities to revisit materials after class. A health professional provided contextual advice on lighting and classroom sightlines. The findings informed a design that pairs guided in-person concept work with replayable signed explanations and tiered asynchronous practice. 
Conclusion: The study specifies accessibility and instructional features for a future model in this setting. Their feasibility and effects on conceptual understanding require testing.