BCSD Mathematics Unit Planning Organizer
Grade 3 – Unit 4
Subject: Mathematics
Unit 4: Area & Perimeter
Grade: Third
Pacing: 4 Weeks Instruct and Assess
1 Week ERI
Total: 5 Weeks
Essential Questions:
1. How can understanding attributes of polygons help us to efficiently calculate perimeter?
2. What is area and how is it measured?
Big Ideas:
1. Rectangles and parallelograms have opposite sides of equal length, so the perimeters of these
shapes can be found by doubling the lengths of adjacent sides and adding those numbers or
adding lengths of two adjacent sides and then doubling that number. A regular polygon has all
sides of equal length, so its perimeter length is the product of one side length and the number
of sides.
2. Area is the amount of two-dimensional space in a bounded region. It is measured by covering
the bounded region with squares (square units), with no gaps or overlaps, and counting the
squares to find the area measurement in square units. Area can also be found by multiplying
the number of squares in each row by the number of rows.
Priority Standards
Supporting Standards
3.MDA.5 Understand the concept of area measurement.
a. Recognize area as an attribute of plane figures;
b. Measure area by building arrays and counting standard unit squares;
c. Determine the area of a rectilinear polygon and relate to multiplication and addition.
3.G.2 Partition shapes into parts with equal areas. Express the area of each part as a unit fraction of
the whole. For example, partition a shape into 4 parts with equal area, and describe the area of each
part as ¼ of the area of the shape.
3.MDA.6 Solve real-world and mathematical problems involving perimeters of polygons,
including finding the perimeter given the side lengths, finding an unknown side length, and
exhibiting rectangles with the same perimeter and different areas or with the same area and
different perimeters.
3.ATO.8 Solve two-step real-world problems using addition, subtraction, multiplication and division of
whole numbers and having whole number answers. Represent these problems using equations with a
letter for the unknown quantity.
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BCSD Mathematics Unit Planning Organizer
Grade 3 – Unit 4
3.MDA.5 Understand the concept of area measurement.
a. Recognize area as an attribute of plane figures;
b. Measure area by building arrays and counting standard unit squares;
c. Determine the area of a rectilinear polygon and relate to multiplication and addition.
Clarification
It is essential for students to:
 Conceptualize area as the amount of two-dimensional space in a bounded region
 Understand that a two-dimensional geometric figure that is covered by a certain number of
same-sized squares without gaps or overlaps can be said to have an area of that number of
square units
 Distinguish the attribute of area from other attributes
 Measure area by building arrays and counting standard unit squares—draw rectangular arrays
of squares and learn to determine the number of squares in each row with increasingly
sophisticated strategies, such as skip-counting the number in each row and eventually
multiplying the number in each row by the number of rows
 Determine the area of a rectangle and relate the process to multiplication and addition—
interpret the measurement of rectangular regions as a multiplicative relationship of the n umber
of square units in a row and the number of rows
 Understand and explain why multiplying the side lengths of a rectangle yields the same
measurement of area as counting the number of tiles that fill the rectangle’s interior (for
example, students might explain that one length tells how many unit squares in a row and the
other length tells how many rows there are)
It is not essential for students to:
 Use the formula to calculate the area of a rectangle
 Calculate the area of polygons that are not rectangles
Concepts (Need to Know)
Skills (Able to Do)
Cognitive Demand
 Area is an attribute of
 Recognize
 Understand
plane figures
 Understand
 Apply
 Concepts of area
measurement –
 A square with a side
length of 1 unit is called a
“unit square” and has
“one square unit” of area
 Unit squares can be used
to measure area
 Area of a plane figure can
be found by covering it
with unit squares, leaving
no gaps or overlaps
3.MDA.6 Solve real-world and mathematical problems involving perimeters of polygons,
including finding the perimeter given the side lengths, finding an unknown side length, and
exhibiting rectangles with the same perimeter and different areas or with the same area and
different perimeters.
Clarification
It is essential for students to:
 Differentiate between area and perimeter
 Understand perimeter as the boundary of a two-dimensional shape
 Understand the perimeter of rectangles as the sum of the lengths of the sides
 Conclude (after many experiences) that rectangles have opposite sides of equal length, so to
find the perimeter, one can double the lengths of adjacent sides and add those numbers or add
lengths of two adjacent sides and double that number
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BCSD Mathematics Unit Planning Organizer
Grade 3 – Unit 4



Find the perimeter when given the side lengths of rectangles
Find an unknown side length of a rectangle when given other side lengths
Find and sketch rectangles with the same perimeter and different areas or the same area and
different perimeters
It is not essential for students to:
 Use the formulas to calculate the areas or perimeters of rectangles
 Calculate the areas or perimeters of polygons that are not rectangles
Concepts (Need to Know)
Skills (Able to Do)
Cognitive Demand
 Real world and
 Solve
 Apply
mathematical problems
involving perimeters of
polygons including:
 finding the perimeter
given the side lengths
 finding an unknown side
length
 exhibiting rectangles with
the same perimeter and
different areas
 exhibiting rectangles with
the same area and
different perimeters
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BCSD Mathematics Unit Planning Organizer
Grade 3 – Unit 4
Vocabulary
Mathematically proficient students communicate precisely by engaging in discussion about their
reasoning using appropriate mathematical language. The terms students should learn to use with
increasing precision within this unit are: attribute, plane figures, rectilinear polygon, perimeter,
area, square unit, formula, partition, length, and width.
*These are the words the teacher should use frequently with instruction and words that students use
when discussing mathematical content. These words are not intended for assessment.
Required Resources
Supplemental Resources
Support Documents:
South Carolina Department of Education
BCSD
My Math*:
Chapter 13: Lessons 3, 4, 5, 6, 7, 8, 9, 10
*These lessons contain activities and ideas that
teachers may find helpful.
Illustrative Mathematics:
3.MDA.5 Finding the Area of Polygons
3.MDA.5 The Square Counting Short Cut
3.MDA.6 Shapes and Their Insides
NCTM Illuminations (PDF Files)
What’s My Area
IGD: Area of a Rectangle
Finding Perimeter and Area
NCTM Articles:
Moyer, Patricia, “Using Representations to Explore
Perimeter and Area,” Teaching Children
Mathematics 8, no. 1 (September 2001): 52–59.
M2 Level 1: Creating the School Measurement Fair
Chapter 2 (Enrichment)
M3 Level 3 What’s the ME in Measurement All
About?
Chapter 1: Lesson 3
Chapter 2: Lessons 2, 3
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