Curriculum / Math / 3rd Grade / Unit 5: Shapes and Their Perimeter / Lesson 15
Math
Unit 5
3rd Grade
Lesson 15 of 16
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Solve a variety of word problems involving area and perimeter.
The core standards covered in this lesson
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 length, and exhibiting rectangles with the same perimeter and different areas or with the same area and different perimeters.
The foundational standards covered in this lesson
3.MD.C.5 — Recognize area as an attribute of plane figures and understand concepts of area measurement.
3.MD.C.6 — Measure areas by counting unit squares (square cm, square m, square in, square ft, and improvised units).
3.MD.C.7 — Relate area to the operations of multiplication and addition.
3.OA.D.8 — Solve two-step word problems using the four operations. Represent these problems using equations with a letter standing for the unknown quantity. Assess the reasonableness of answers using mental computation and estimation strategies including rounding. This standard is limited to problems posed with whole numbers and having whole-number answers; students should know how to perform operations in the conventional order when there are no parentheses to specify a particular order (Order of Operations).
The essential concepts students need to demonstrate or understand to achieve the lesson objective
Solve word problems involving area and perimeter, including given the length and width of a rectangle, determine its area and perimeter; given the area and one dimension of a rectangle, determine its perimeter; and given the perimeter and one dimension of a rectangle, determine its area (MP.4).
Suggestions for teachers to help them teach this lesson
Students solve word problems involving both perimeter and area in this lesson, thus connecting the additional cluster content of perimeter to the major cluster content of area.
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Tasks designed to teach criteria for success of the lesson, and guidance to help draw out student understanding
Claudia is redecorating her bedroom, which is in the shape of a rectangle that is 8 feet long and 9 feet wide. She needs to buy new carpeting and wants to put baseboards around the border of her bedroom.
a. How much carpeting should Claudia order?
b. How much baseboard should Claudia order?
The length of a rectangle is 6 cm and its perimeter is 16 cm. What is the area of the rectangle in square centimeters?
Problem Set
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A task that represents the peak thinking of the lesson - mastery will indicate whether or not objective was achieved
The area of a rectangular bulletin board is 20 square feet. The length of the bulletin board is 5 feet. What is the perimeter of the bulletin board?
Mrs. Rothschild wants to put up a new bulletin board outside of her classroom. She wants the bulletin board to be 4 feet tall and 7 feet long. The bulletin board will be covered with cork and will have a metal frame around it.
a. How much metal framing does Mrs. Rothschild need?
b. How much cork does Mrs. Rothschild need?
The Extra Practice Problems can be used as additional practice for homework, during an intervention block, etc. Daily Word Problems and Fluency Activities are aligned to the content of the unit but not necessarily to the lesson objective, therefore feel free to use them anytime during your school day.
Extra Practice Problems
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Help students strengthen their application and fluency skills with daily word problem practice and content-aligned fluency activities.
Lesson 14
Lesson 16
Topic A: Attributes of Two-Dimensional Shapes
Compare and classify polygons.
3.G.A.1
Compare and classify quadrilaterals.
Draw shapes with specified attributes.
Reason about composing and decomposing polygons using tangrams.
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Topic B: Understanding Perimeter
Understand perimeter to be the boundary around a two-dimensional shape. Compare perimeters of various polygons using concrete non-standard units.
3.MD.D.8
Find perimeter of polygons whose sides are marked with unit length marks by counting the unit lengths.
Find perimeter of shapes with all side lengths labeled.
Find perimeter by measuring side lengths in whole number units.
Find perimeter of regular polygons and of rectangles when some side lengths are not given.
Solve word problems involving finding perimeter given the side lengths.
Find side lengths of regular polygons and of rectangles when given perimeter and other side lengths.
Solve more complex word problems involving perimeter, such as finding a missing side length given perimeter and other side lengths.
Topic C: Distinguishing Between Area and Perimeter
Find rectangles with the same area and different perimeters.
Find rectangles with the same perimeter and different areas.
Reason about composing and decomposing polygons with various areas and perimeters using tetrominoes.
3.G.A.1 3.MD.D.8
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