3.MD.8 - About the Math, Learning Targets, and Rigor

Grade 3 Measurement

3.MD.D.8

About the Math

Full Standard

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.

 

Measurement Topic

This standard is reported on the report card in these quarters as follows:

3rd Grade Students Learning 3rd Grade Standards
Quarter 1 Quarter 2 Quarter 3 Quarter 4

 

 

Report Card Measurement Topic: Demonstrates understanding of measurement, data and geometry.

 

 

Learning Targets

  • Describe a polygon.
  • Describe perimeter.
  • Find the perimeter of polygons when given the lengths of all sides.
  • Find the unknown side lengths of polygons when given the perimeter.
  • Explain how rectangles with the same perimeter can have different areas and how rectangles with the same area can have different perimeters.
  • Solve perimeter word problems.

 

About the Math

The perimeter is the distance around a figure or shape. If the shape is a polygon, to find the perimeter, add the length of the sides.  Shapes with the same perimeter can have different areas. Shapes with the same area can have different perimeters. Students should be given opportunities to discover the relationship between area and perimeter and what happens when you hold either the area or perimeter constant. Essential vocabulary for this standard includes: area, perimeter, and polygons. Visit the online dictionary Links to an external site. for vocabulary support.

Polygon: a flat, closed shape with sides, no curves

Perimeter: the distance around a shape; the total length of the outer edge around the shape

Area: the covering of a flat surface such as the space within a shape; how many of a chosen unit of area (such as square units) it takes to cover the object without gaps or overlaps

 

 

Progression of Standard within Grade 3

This progression informs how to develop the standard within the grade level. This progression is provided by HCPSS Elementary Mathematics.

Progression Throughout Year
Quarter 1 Quarter 2 Quarter 3 Quarter 4
     
  • Describe a polygon.
  • Describe perimeter.
  • Find the perimeter of polygons when given the lengths of all sides.
  • Find the unknown side lengths of polygons when given the perimeter.
  • Solve perimeter word problems.

 
  • Describe a polygon.
  • Describe perimeter.
  • Find the perimeter of polygons when given the lengths of all sides.
  • Find the unknown side lengths of polygons when given the perimeter.
  • Explain how rectangles with the same perimeter can have different areas and how rectangles with the same area can have different perimeters.
  • Solve perimeter word problems.

Progression of this Standard Across Grades

This progression is informed by the Achieve the Core Coherence Map. Links to an external site. Information is not the complete standard.

Progression Across Grades
Grade 2 Grade 4
  • Recognize and draw polygons and other figures ( 2.G.A.1 )
  • Measure lengths (2.MD.A.1)
  • Apply the perimeter formulas for rectangles in real world and mathematical problems (4.MD.3 )

 

 

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Instructional Tasks

 TASKS

These tasks can be used with small group or whole group instruction.

  • Distribute a geoboard to each student. Ask students to create a square with side lengths of 3 units. Ask students to describe what they notice about their shape. "What can you say about the inside of the square?" "How can you describe the outline (where the rubber bands are)?" Ask students to make a rectangle of their choice. Have students turn and talk to a neighbor about their shape (inside and outside). Together generate the definitions of perimeter and area and chart. 
  • Working with geoboards, tell students that they will be simulating the building of fences to represent perimeter. Show students pictures of fences in the real world and when/how people would use fences. Ask students to make a rectangular yard with a perimeter of 12 units, 8 units and 14 units. Compare representations. "What addition equation could we write to represent the perimeter?" Add these ideas to the anchor chart.
  • Distribute color tiles to each student. Discuss how we can build irregular shapes and still find the perimeter. Ask students to build a shape using 8 color tiles that is a polygon, but not a rectangle. Ask students to think about what the perimeter is of the shape they created. Discuss and compare the different shapes and their perimeters. Show the students a 4x2 rectangle with color tiles. "How does the perimeter of the rectangle compare to the perimeter of the irregular shapes?"
  • There are 2 shapes with the same area of 15 square units. Their perimeters are very different. What could the shapes be?
  • There are 2 shapes with the perimeter of 20 units. Their areas are different. What could the length and width of the shapes be?
  • The construction crew was building a playground with a perimeter of 96 feet. The students were trying to figure out what it was going to look like. The playground was not in the shape of a square and the longest side was 32 feet long. What could the playground look like and what could each of the measurements be?
  • The sandbox has a perimeter of 90 inches. It is not a square and one of the sides in 15 inches. What could the sandbox look like and what are the measurements of the the sides?
  • The perimeter of a rectangular chalkboard is 50 ft. The top of the chalkboard is 17 ft. What are the lengths of the other 3 sides?
  • Two shapes each have an area of 24 square units.  They each have a different perimeter.  What could each perimeter be?
  • A farmer is building a fenced in area for the farm animals.  He wants to build a space with the largest area he can.  The shape of the space needs to be a rectangle.  He has enough fence material to create a section with a perimeter of 48 feet. What is the largest area he can make with the material he has.  What would the length and width of the space be?
  • Tom says that if two figures have different perimeters, they can't have the same area.  Do you agree?  If not, explain why.
  • You are designing a rectangular play pen for your dog.  You have 18 yards of fencing.  Use the orange Ang Legs to represent 18 yards of fencing.  Design different options for your dog's rectangular play pen.  Label the different side measurements and record the designs in your notebook.  

 

Slide-Based Tasks 

These links are HCPSS created instructional tasks. These tasks are provided in Google slides.  These tasks should be used for inspiration and resources, but instruction should start with students having the opportunity to engage with the math first (often involving physical and/or visual models) followed by discussion and explicit instruction to ensure student understanding.

Module 12 • Perimeter and Understanding Area and Basic Facts (3s)

Solve Problems Involving Perimeter:

Module 13 • Area & Perimeter and Basic Facts (6s and All)

Solve Problems Involving Perimeter (and Area):

 

 

Additional Tasks

These links provide instructional ideas connected to this standard. 

Blogged.

 

Tasks From Print Resources

These publications have been provided for each school. They are typically stored in team closets or the media center. Check with your team leader if you cannot find them. 

Print Resources
Book Thumbnail Book Title Grade Pages

Teaching Student-Centered Mathematics 

 K-3   

Two-Piece Shapes, Activity 8.8, Page 234
Rectangle Comparison- No Units, Activity 8.9, Page 235
Fill and Compare, Activity 8.11, Page 236
Rectangle Compare- Square Units, Activity 8.12, Page 237

Teaching Student-Centered Mathematics 

 3-5

Fixed Perimeters, Activity 9.7, Page 265
Expanded Lesson: Fixed Areas, Pages 288-289 

 

 

Hands On Standards (1-2) 

 

 

 

 

 
Hands-On Standards (3-4) 

3-4

pgs 112-113 (Exploring Perimeter)

pgs 114-115 (Measuring Perimeter)

pgs 116-117 (Solving Perimeter Problems)

 

 

pg  128, (Perimeter of Shapes)

pg 130, (Building a Perimeter)
  Groundworks Reasoning with Geometry (2)

  pages 88-95 (Stretching and Shrinking)
 

Super Source: Color Tiles K-2

Super Source: Cuisenaire Rods K-2

Super Source: Geoboards K-2

Super Source: Pattern Blocks K-2

Super Source: Color Tiles 3-4

3

pp 48, 66

p 37

pp 8, 18, 26-29, 42

pp 18-21, 74, 78, 86-89

pp 22-25, 30-33
 

Roads to Reasoning (1)

Roads to Reasoning (2)

Roads to Reasoning (3)

Roads to Reasoning (4)

 2-3

"Toy Hunt", p 55

"Way Around", p 83

pp 52, 67

pp 52, 82
  Brain-Compatible Activities
for Mathematics 2-3

Brain-Compatible Activities
for Mathematics 4-5

 (102-106)

 

 (99-102)

Math In Practice

Teaching Third-Grade Math

 3

Module 15

 

More Ideas

 

 

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Independent Work

Centers

These print resources can be used during independent or center time. These resources could also be used as lesson seeds.

 

 

 

Independent Practice/Homework

These resource sheets can be used for independent practice or homework. They are intended to reinforce procedures and concepts. They should not be used as a source of direct instruction or whole-group practice.

 

 

 

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Assessment

Learning Targets

  • Describe a polygon.
  • Describe perimeter.
  • Find the perimeter of polygons when given the lengths of all sides.
  • Find the unknown side lengths of polygons when given the perimeter.
  • Explain how rectangles with the same perimeter can have different areas and how rectangles with the same area can have different perimeters.
  • Solve perimeter word problems.

Learning targets identify what students should be able to do.The rubric can be applied to tasks and observations for assessment and/or grading. 

 

 

 

 

 

 

Visit the SBIR (Standards Based Instruction and Reporting) tab in Course Essentials for more information and clarification. There you will find the measurement topic crosswalk, report card comments, links to professional learning/resources and guidance.  

 

 

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 This course content is offered under a CC Attribution Non-Commercial Share Alike Links to an external site. license. Content in this course can be considered under this license unless otherwise noted.