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Grade 4 Math Units

Unit Plan 12 (Grade 4 Math): Perimeter & Area—Rectangles in the Real World

Apply area and perimeter formulas for rectangles to solve real-world design and tiling problems, using models and correct units to justify solutions and check reasonableness.

Dr. Michael Kester-Haynes

• 6 min read
Unit Plan 12 (Grade 4 Math): Perimeter & Area—Rectangles in the Real World

Focus: Apply area and perimeter formulas for rectangles; solve design/tiling contexts with clear units, models, and reasonableness checks.

Grade Level: 4

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

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

I. Introduction

Students build a durable understanding of perimeter (distance around) and area (space covered) for rectangles. They connect tiling and arrays to formulas (A = length × width, P = 2 × (length + width)), solve real-world design problems, keep units precise (e.g., cm, cm²), and justify choices with diagrams and equations.

Essential Questions

  • When do I need perimeter and when do I need area?
  • How do tiles, grids, and arrays help explain the formulas for rectangles?
  • How do units and labels show that my solution is reasonable?

II. Objectives and Standards

Learning Objectives — Students will be able to:

  1. Explain and use perimeter as total distance around and area as number of square units covering a rectangle.
  2. Model rectangles with tiles, grids, and arrays to justify A = length × width.
  3. Compute P = 2 × (length + width) and find missing side lengths from given perimeter or area.
  4. Solve design/tiling problems and write equations with an unknown that match the situation.
  5. Communicate answers with correct units (cm, m, in, ft) and square units (cm², m², in², ft²) and check reasonableness.

Standards Alignment — CCSS Grade 4 (spiral across the unit)

  • 4.MD.3: Apply the area and perimeter formulas for rectangles in real world and mathematical problems.
  • Connections: 4.OA.3 (multi-step problems, light), 4.NBT.4–5 (multi-digit computation, light), 4.MD.1 (measurement units awareness, light).
  • Mathematical Practices (MP.1–MP.8) threaded throughout.

Success Criteria — Student Language

  • I can tell if a problem needs perimeter or area and explain why.
  • I can model a rectangle (tiles/grid) and use A = length × width or P = 2 × (length + width) correctly.
  • I can label units and square units, and use an estimate to check if my answer makes sense.