📂 Decomposing Rectangles Lesson (Google Slides Lesson)

📐 Decomposing Rectangles to Find Area | 3rd Grade Area Lesson

Are your students ready to move beyond basic rectangles and tackle composite figures with confidence? This engaging, step-by-step PowerPoint lesson teaches students how to decompose composite figures into non-overlapping rectangles to determine total area using the formula Length × Width.

Perfect for whole-group instruction, math workshop, guided practice, and test prep!

🎯 Learning Focus

Students will:

✔ Break apart (decompose) composite figures into two rectangles
✔ Identify and label length (L) and width (W)
✔ Multiply L × W to find the area of each rectangle
✔ Add partial areas to determine total area
✔ Understand why diagonal cuts are NOT allowed
✔ Apply strategies to real-world problem situations

📘 What’s Included

This comprehensive PowerPoint includes:

✏️ Clear Concept Instruction

• Definition of a rectangle (2D shape, 4 right angles, opposite sides equal)
• What area means (square units explained clearly for 3rd grade)
• Visual modeling of L × W
• Step-by-step mini-lesson examples

🧠 Multiple Decomposition Strategies

Students see how the same figure can be broken apart in more than one way while still finding the same total area.

🧩 Guided Practice Slides

• Structured modeling
• Fill-in templates for L, W, and area
• Student discussion prompts

🌎 Real-World Word Problems

Students solve area problems involving:

• Playgrounds
• Pools
• Gardens
• Tool sheds
• Restaurants
• Pantry sections
• Library spaces

All problems are multiple choice for easy assessment!

🎟 Exit Tickets (3 Included!)

Quick checks for understanding to assess mastery before independent practice or testing.

📊 Skills Covered

• Area of rectangles
• Composite figures
• Decomposing shapes
• Multiplying to find area
• Adding partial areas
• Counting unit squares
• Mathematical reasoning & justification

🏫 Perfect For:

• 3rd Grade Math
• Whole group instruction
• STAAR prep
• Small group intervention
• Math centers
• Digital learning

💡 Why Teachers Love This Resource

⭐ Clear visuals and modeling
⭐ Student-friendly language
⭐ Scaffolded instruction
⭐ Multiple problem types
⭐ Real-world application
⭐ Easy-to-use Google Forma

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