Inclusive opportunities for students with extensive support needs are a predictor of both in school and post-school outcomes; however, successful inclusion must consider how student learning needs and evidence-based practices are incorporated. Potential exists to align evidence-based instruction for students with extensive support needs utilizing the Multi-tiered System of Support (MTSS) framework for all students within the inclusive math classroom across tier 2 and tier 3. Findings of this single-case, multiple probe, across student research study suggest that embedded instruction is an effective and feasible instructional practice to support specially designed instruction in early numeracy within a tiered support model for students with extensive support needs in the inclusive math classroom. Based upon our findings, we sought to develop a model of practice for specially designed instruction (SDI) within tiered systems of support for students with extensive support needs that educational teams, school administrators, and policymakers can use to design math instruction within inclusive settings.