Examine the parts of a whole to define or model a system.
With 1.5D, Grade 1 students practice Systems: parts & wholes in multiple representations and contexts.
Aligned tasks under 1.5D balance fluency and reasoning so students can explain decisions about Systems: parts & wholes.
Use short exit tickets and tasks where students explain decisions, show multiple representations, or justify answers—directly aligned to 1.5D.
It lays groundwork for the next grade by deepening accuracy and flexibility with Systems: parts & wholes, so students can tackle more complex problems later.
Students may rely on procedures without reasoning or mix key terms. Build in quick oral explanations, error analysis, and vocabulary supports tied to 1.5D.
Standard 1.5D describes the essential skills and understandings for Systems: parts & wholes in Grade 1. It clarifies the learning outcomes and what successful work looks like.
