Curriculum / Math / 3rd Grade / Unit 4: Area / Lesson 14
Math
Unit 4
3rd Grade
Lesson 14 of 14
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Recognize area as additive. Find the area of a complex composite figure.
The core standards covered in this lesson
3.MD.C.7.D — Recognize area as additive. Find areas of rectilinear figures by decomposing them into non-overlapping rectangles and adding the areas of the non-overlapping parts, applying this technique to solve real world problems.
The essential concepts students need to demonstrate or understand to achieve the lesson objective
Suggestions for teachers to help them teach this lesson
The lesson includes composite figures that are more complex than previous days, such as composite figures that must be decomposed into more than two rectangles or composite figures whose easiest strategy to find the area of is using a subtractive rather than additive strategy (such as Anchor Task #2). Every problem will provide enough information for either an additive or subtractive strategy to be used to solve, though, so that students aren’t expected to show success with the subtractive strategy.
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Tasks designed to teach criteria for success of the lesson, and guidance to help draw out student understanding
25-30 minutes
Veronica is making a poster for science class.
What is the total area, in square feet, of the poster?
Setsuko is redoing a room and wants to put wallpaper on a wall that has a window. The wall with the window, shaded, are shown in the diagram below.
How many square feet of wallpaper will Setsuko use on the wall?
15-20 minutes
Problem Set
Unlock the answer keys for this lesson's problem set and extra practice problems to save time and support student learning.
A task that represents the peak thinking of the lesson - mastery will indicate whether or not objective was achieved
5-10 minutes
Mrs. Allen wants to cover one wall in her office with butcher block paper for students to draw on. There is a door on the wall, which she won’t cover with butcher block paper. Here is a picture of Mrs. Allen’s wall:
How many square feet of butcher block paper will Mrs. Allen need? Show or explain your work.
An example response to the Target Task at the level of detail expected of the students.
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 13
Topic A: Understanding Concepts of Area
Understand that area is an attribute of plane figures that is a measure of how much flat space an object takes up. Find the area of a figure using pattern blocks, which can be used as concrete non-standard units.
3.MD.C.5 3.MD.C.6
Understand that area is measured using square units. Find the area of a figure using square tiles.
Find the area of a rectangle by counting unit squares on grids.
Find the area of a rectangle with incomplete information about its rows and columns of square units.
3.MD.C.6 3.MD.C.7.A
Find the area of a rectangle that has been superimposed over a grid.
Find the area of a rectangle through multiplication of the side lengths.
3.MD.C.7.A 3.MD.C.7.B
Understand standard units for measuring area, including square inches, square centimeters, square feet, and square meters, and choose an appropriate unit to measure the area of various rectangles.
3.MD.C.6
Measure the side lengths of a rectangle to find its area.
3.MD.C.7.B
Solve word problems involving area.
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Topic B: The Distributive Property and Composite Area
Compose and decompose a rectangle, seeing and making use of the idea that the sum of the areas of the decomposed rectangle is equal to the area of the composed rectangle.
3.MD.C.7.C
Apply the distributive property as a strategy to find the total area of a large rectangle.
Recognize area as additive. Find the area of a composite figure as shown on a grid or with all side lengths labeled.
3.MD.C.7.D
Recognize area as additive. Find the area of a composite figure when not all dimensions are given.
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