Area

Lesson 6

Math

Unit 4

3rd Grade

Lesson 6 of 14

Objective


Find the area of a rectangle through multiplication of the side lengths.

Common Core Standards


Core Standards

  • 3.MD.C.7.A — Find the area of a rectangle with whole-number side lengths by tiling it, and show that the area is the same as would be found by multiplying the side lengths.
  • 3.MD.C.7.B — Multiply side lengths to find areas of rectangles with whole-number side lengths in the context of solving real world and mathematical problems, and represent whole-number products as rectangular areas in mathematical reasoning.

Foundational Standards

  • 2.G.A.2
  • 2.MD.A.1
  • 3.OA.C.7

Criteria for Success


  1. Find the area of a rectangle shown pictorially with labeled dimensions by multiplying its length and width, explaining how that is the same as counting individual units (MP.3, MP.7).
  2. Find the side length of a rectangle shown pictorially with labeled dimensions given its area and one side length using the relationship between multiplication and division. 

Tips for Teachers


As a supplement to the Problem Set, students can play “Raging Rectangles,” from Building Conceptual Understanding and Fluency Through Games (Grade 3) by the North Carolina Department of Public Instruction.

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Anchor Tasks

25-30 minutes


Problem 1

a.   The tick marks on the sides of the rectangle below are 1 unit apart.

What is the area in square units? Show or explain how you know.

b.   The top side of this rectangle is marked off in unit lengths. The left side is labeled with the length in units.

What is the area in square units? Show or explain how you know.

Guiding Questions

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Student Response

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References

Illustrative Mathematics Illustrative Math Grade 3 Unit 2 Lesson 8 Activity 2

SetIllustrative Math Grade 3 Unit 2 Lesson 8 Activity 2, accessed on Sept. 23, 2022, 2:13 p.m., is licensed by Illustrative Mathematics under either the CC BY 4.0 or CC BY-NC-SA 4.0. For further information, contact Illustrative Mathematics.

Modified by Fishtank Learning, Inc.

Problem 2

a.   Write a multiplication expression that represents the area of the following figure. Then find its area.

b.   Frederick draws another rectangle with the same area. What might the length and width of Frederick's rectangle be?

Guiding Questions

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Student Response

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Problem 3

a.   The area of the rectangle below is 42 square units. Find the missing side length.

b.   Explain how you can use either multiplication or division to solve Part (a).

Guiding Questions

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Student Response

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Problem Set

15-20 minutes


Discussion of Problem Set

  • In what way is the area of #2(b) related to the area of #2(a)? How could you use the side lengths to help you figure out that 8 x 7 is double 4 x 7? 
  • Which shape in #2 is a square? How do you know? 
  • How are the rectangles in #2(a) and #5(c) similar? How are they different? 
  • Was anyone able to tell which two tables in #7 had the same area before multiplying them? How was that possible? 
  • Why is there a connection between a rectangle’s side lengths and its area? 

Target Task

5-10 minutes


Problem 1

A rectangle has the measurements shown. Select the three ways to calculate the area of the rectangle in square units.

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Student Response

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Problem 2

Find the side length of the rectangle below.

Student Response

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Additional Practice


The Extra Practice Problems can be used as additional practice for homework, during an intervention block, etc. Daily Word Problems and Fluency Activities are aligned to the content of the unit but not necessarily to the lesson objective, therefore feel free to use them anytime during your school day.

Word Problems and Fluency Activities

Word Problems and Fluency Activities

Help students strengthen their application and fluency skills with daily word problem practice and content-aligned fluency activities.

Next

Understand standard units for measuring area, including square inches, square centimeters, square feet, and square meters, and choose an appropriate unit to measure the area of various rectangles.

Lesson 7
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Lesson Map

A7CB09C2-D12F-4F55-80DB-37298FF0A765

Topic A: Understanding Concepts of Area

Topic B: The Distributive Property and Composite Area

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