CCSS.Math.Content.3.MD.D

CCSS.Math.Content.3.MD.D is a cluster heading. These are the individual standards under it.

• CCSS.Math.Content.3.MD.D.8

  Solve real world and mathematical problems involving perimeters of polygons, including finding the perimeter given the side lengths, finding an unknown side len...

01

What Students Need to Do

Students measure the boundary of a flat shape and add its side lengths. They tell when a problem needs linear units for distance or square units for covered space.

02

What Mastery Looks Like

Students find the distance around regular and irregular shapes by adding all side lengths. They label perimeter with linear units and area with square units. They can explain that shapes may share a perimeter but have different areas.

03

Common Misconceptions

Students may confuse the distance around a shape with the space inside it. They may skip sides, add only length and width, or label perimeter with square units.

04

How to Assess It

Exit ticket: Draw a rectangle that is 4 units by 7 units. Find its perimeter and area, label the units, and explain why the units differ.

1. 01

   Give pairs string, rulers, and square tiles to measure the boundary and cover the inside of three cardboard shapes.

2. 02

   Ask, “Can two rectangles have the same perimeter but different areas?” Students draw examples and explain their reasoning.

3. 03

   Play Perimeter Match: students pair shape cards with perimeter cards, then check by adding every side length.

4. 04

   Measure the border and surface of a classroom bulletin board, then decide whether trim or paper uses each measurement.

• CCSS.Math.Content.4.MD.C

  Geometric measurement: understand concepts of angle and measure angles.

• CCSS.Math.Content.3.MD.C

  Geometric measurement: understand concepts of area and relate area to multiplication and to addition.

• CCSS.Math.Content.3.MD.C.5

  Recognize area as an attribute of plane figures and understand concepts of area measurement.

• CCSS.Math.Content.4.G.A.2

  Classify two-dimensional figures based on the presence or absence of parallel or perpendicular lines, or the presence or absence of angles of a specified size. ...