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Grade 3 Math Units

Unit Plan 18 (Grade 3 Math): Midyear Synthesis—Facts, Area/Perimeter, and NBT

Mixed 3rd-grade math review: practice fact fluency, area vs. perimeter, rounding, and two-step word problems using models, equations, and estimates.

Dr. Michael Kester-Haynes

• 5 min read
Unit Plan 18 (Grade 3 Math): Midyear Synthesis—Facts, Area/Perimeter, and NBT

Focus: Mixed tasks blending fact fluency, area/perimeter, rounding, and two-step problems; students plan, solve, and justify using models, equations, and estimates.

Grade Level: 3

Subject Area: Mathematics (Integrated Review • OA • NBT • MD)

Total Unit Duration: 5 sessions (one week), 45–60 minutes per session

I. Introduction

Students pull together fall learning: multiplication/division facts, area as square units, perimeter as boundary length, rounding for estimation, and two-step problem solving. They choose strategies, show representations, and defend reasonableness.

Essential Questions

  • How do I choose an efficient strategy (property, model, or algorithm) for this problem?
  • When should I round to plan or to check, and when should I compute exactly?
  • How do representations (arrays, area models, number lines, equations) make my reasoning clear?

II. Objectives and Standards

Learning Objectives — Students will be able to:

  1. Use properties of operations (commutative/associative/distributive) to build and explain fact fluency.
  2. Compute and justify area (square units) and perimeter (total boundary) in real contexts.
  3. Round numbers (nearest 10/100) to estimate, then compute to confirm (within 1,000).
  4. Solve two-step problems with an equation using a letter for the unknown and check reasonableness.
  5. Communicate with precision: correct units, labels, and clearly chosen models.

Standards Alignment — CCSS Grade 3 (spiral across the unit)

  • 3.OA.1–2: Interpret products/quotients in context.
  • 3.OA.5–9: Use properties and patterns; develop fact fluency and analyze errors.
  • 3.NBT.1–2: Round to nearest 10/100; fluently add/subtract within 1,000.
  • 3.MD.5–8: Area as unit squares; area formula for rectangles; decompose figures; perimeter in context.
  • Mathematical Practices: MP.1–MP.6 (perseverance, reasoning, modeling, tools, precision).

Success Criteria — Student Language

  • I can pick a strategy (property/model) and explain why it fits the problem.
  • I can use rounding to estimate and then compute to check my answer.
  • I can label area in square units and perimeter in length units, and write an equation with an unknown.