Unit Plan 11 (Grade 2 Math): Adding Several Two-Digit Numbers

Focus: Add up to four two-digit numbers using place-value strategies, compose/decompose tens, and the properties of operations; maintain precision and reasonableness.

Grade Level: 2

Subject Area: Mathematics (Number & Operations in Base Ten • Operations & Algebraic Thinking)

Total Unit Duration: 5 sessions (one week), 35–45 minutes per session

I. Introduction

Students build fluency adding several two-digit numbers in real contexts (supplies, steps, distances). They select and justify methods—break apart tens/ones, make a ten, group friendly pairs (associative), and open number line—while checking reasonableness with rounding or different orders of addition.

Essential Questions

• How does place value help me add several numbers efficiently?
• How can I use the associative and commutative properties to make friendly sums?
• How do I check for precision and reasonableness when many addends are involved?

II. Objectives and Standards

Learning Objectives — Students will be able to:

1. Add 2–4 two-digit addends using place-value decomposition and compose/decompose tens.
2. Rearrange and group addends (use the associative/commutative properties) to create friendly tens and reduce errors.
3. Represent thinking with equations, open number lines, or base-ten models, and explain why the method works.
4. Check precision with estimation (round to nearest ten) and by adding in a different order.

Standards Alignment — CCSS Grade 2 (spiral across the unit)

• 2.NBT.6: Add up to four two-digit numbers using strategies based on place value and properties of operations.
• MP.1: Make sense of problems and persevere in solving them.
• MP.6: Attend to precision. (MP.3 reasoning appears in explanations/peer critique.)

Success Criteria — Student Language

• I can break apart numbers into tens and ones and compose a new ten when I add.
• I can group addends to make friendly tens and tell why that helps.
• I can show my work with a model (blocks, chart, open number line), keep labels clear, and check my answer.