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First Grade mathematics is about
- Developing understanding of addition, subtraction, and strategies for addition and subtraction within 20
- Developing understanding of whole number relationships and place value, including grouping in tens and ones
- Developing understanding of linear measurement and measuring lengths as iterating length units
- Reasoning about attributes of, and composing and decomposing geometric shapes.

About Downloadable Resources

A Story of Units: Curriculum Map and Overview for Grades P-5: provides teachers with a clear picture of the modules at each grade level from Pre-Kindergarten to Grade 5.

How to Implement A Story of Units: provides additional information on how teachers can implement this currciulum in their classrooms. It introduces teachers to A Story of Units and it delineates the Common Core approach to mathematics, assessment, differentiating instruction, and mathematical models. The lesson structure utilized in A Story of Units which encompasses all three aspects of rigor is also detailed.

CCLS Checklist for A Story of Units: includes grade-level charts providing an at-a-glance view of when each standard is addressed. Note that, for grades K–5, standards included in clusters designated as Major Emphases by the New York State Education Department are followed by an asterisk (*).

Scaffolding Instruction for ELLs: Resource Guide for Mathematics: provide guidance to educators on how to take the c

Lesson 15 - Model subtraction of 9 (continued)