Videos, examples, and solutions to help Grade 3 students learn how to construct rectangles with a given perimeter using unit squares and determine their areas.

Common Core Standards: 3.MD.4, 3.MD.8, 3.G.1

Related Topics:

Lesson Plans and Worksheets for Grade 3,

Lesson Plans and Worksheets for all Grades,

More Lessons for Grade 3,

Common Core For Grade 3

New York State Common Core Math Grade 3, Module 7, Lesson 20, Lesson 21

Download the Worksheets for Grade 3, Module 7, lesson 20 (pdf)

Download the Worksheets for Grade 3, Module 7, lesson 21 (pdf)

Concept Development

How to find rectangles that have a perimeter of 16 units?

P = 2 × (L + W)

Lesson 20 Homework

1. Cut out the unit squares above. Then, use them to make as many rectangles as you can with a perimeter of 10 centimeters.

a. Estimate to draw your rectangles below. Label the side lengths of each rectangle.

b. Find the areas of the rectangles in Part (a) above.

3. Katie draws a square that has a perimeter of 20 centimeters.

a. Estimate to draw Katie’s square below. Label the length and width of the square.

b. Find the area of Katie’s square.

c. Estimate to draw a different rectangle that has the same perimeter as Katie’s square.

d. Which shape has a greater area, Katie’s square or your rectangle?

Lesson 21 Homework

1. Margo finds as many rectangles as she can with a perimeter of 14 centimeters.

a. Shade Margo’s rectangles on the grid below. Label the length and width of each rectangle.

b. Find the areas of the rectangles in Part (a) above.

c. The perimeters of the rectangles are the same. What do you notice about the areas?

2. Tanner uses unit squares to build rectangles that have a perimeter of 18 units. He creates the chart below to record his findings.

a. Complete Tanner’s chart. You might not use all the spaces in the chart.

b. Explain how you found the widths and lengths in the chart above.

3. Jason and Dina both draw rectangles with perimeters of 12 centimeters, but their rectangles have different areas. Explain with words, pictures, and numbers how this is possible.

You can use the free Mathway calculator and problem solver below to practice Algebra or other math topics. Try the given examples, or type in your own problem and check your answer with the step-by-step explanations.

Common Core Standards: 3.MD.4, 3.MD.8, 3.G.1

Related Topics:

Lesson Plans and Worksheets for Grade 3,

Lesson Plans and Worksheets for all Grades,

More Lessons for Grade 3,

Common Core For Grade 3

New York State Common Core Math Grade 3, Module 7, Lesson 20, Lesson 21

Download the Worksheets for Grade 3, Module 7, lesson 20 (pdf)

Download the Worksheets for Grade 3, Module 7, lesson 21 (pdf)

Concept Development

How to find rectangles that have a perimeter of 16 units?

P = 2 × (L + W)

Lesson 20 Homework

1. Cut out the unit squares above. Then, use them to make as many rectangles as you can with a perimeter of 10 centimeters.

a. Estimate to draw your rectangles below. Label the side lengths of each rectangle.

b. Find the areas of the rectangles in Part (a) above.

3. Katie draws a square that has a perimeter of 20 centimeters.

a. Estimate to draw Katie’s square below. Label the length and width of the square.

b. Find the area of Katie’s square.

c. Estimate to draw a different rectangle that has the same perimeter as Katie’s square.

d. Which shape has a greater area, Katie’s square or your rectangle?

1. Margo finds as many rectangles as she can with a perimeter of 14 centimeters.

a. Shade Margo’s rectangles on the grid below. Label the length and width of each rectangle.

b. Find the areas of the rectangles in Part (a) above.

c. The perimeters of the rectangles are the same. What do you notice about the areas?

2. Tanner uses unit squares to build rectangles that have a perimeter of 18 units. He creates the chart below to record his findings.

a. Complete Tanner’s chart. You might not use all the spaces in the chart.

b. Explain how you found the widths and lengths in the chart above.

3. Jason and Dina both draw rectangles with perimeters of 12 centimeters, but their rectangles have different areas. Explain with words, pictures, and numbers how this is possible.

Rotate to landscape screen format on a mobile phone or small tablet to use the **Mathway** widget, a free math problem solver that **answers your questions with step-by-step explanations**.

You can use the free Mathway calculator and problem solver below to practice Algebra or other math topics. Try the given examples, or type in your own problem and check your answer with the step-by-step explanations.

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