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Lesson Objective: The lesson is aligned to the Common Core State Standards for Mathematics – 3.MD.7c Geometric Measurement – Use area models to represent the distributive property.
Materials Required: graph paper, calculator
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Now look at Rectangle 2 and Rectangle 3 shown on the grid.
5. Rectangle 2 has Side a and Side b. Identify the lengths of the two sides of Rectangle 2.
6. Rectangle 3 has Side a and Side c. Identify the lengths of the two sides of Rectangle 3.
7. Find the areas of Rectangle 2 and Rectangle 3.
8. Complete the chart.
9. What is the area of Rectangle 1?
10. What is the sum of the areas of Rectangle 2 and Rectangle 3?
11. Compare the area of Rectangle 1 with sides a and (b + c) and the sum of the areas of Rectangle 2 and Rectangle 3.
12. Write a statement about the comparison.
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1. 5 units
2. 7 units
3. 35 square units
5. 5 units and 3 units
6. 5 units and 4 units
7. 15 square units and 20 square units
9. 35 square units
10. 15 + 20 = 35 square units
11. The area of Rectangle 1 with sides 5 and (3 + 4) is 35. The sum of the areas of Rectangle 2, 15 square units, and Rectangle 3, 20 square units, is 35 square units.
12. The area of Rectangle 1 is equal to the sum of the areas of Rectangle 2 and Rectangle 3.
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Download Lesson with Individual or Group Work
To view the Individual or Group Work segment of this lesson, please download it here. Group work is at the end of the lesson.
Grade 3 Math Lessons on Geometric Measurement
- Finding the Area of Figures using Unit Squares: Grade 3 Math Lesson
- Finding the Area of Figures using Unit Squares: 3rd Grade Math
- 3rd Grade Math: Finding the Area of Rectangular Figures using Multiplication
- Finding the Area of Rectangular Figures in Real World Mathematical Problems: Grade 3 Lesson
- Finding Area using a Model of the Distributive Property: Math Lesson for Grade 3
- Finding the Area with Decomposition and Addition: 3rd Grade Math Lesson with Assessment