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

Grade 3 Measurement

3.MD.D.8

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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