This unit builds on students’ prior knowledge of finding area of rectangles to develop an understanding that area is additive and to learn how to find the area of other figures. Students will learn to find area of triangles, special quadrilaterals and other polygons (by decomposing into rectangles or triangles). Students will learn to find area of irregular figures by decomposing the figure into regions of known or equal areas. Students sometimes struggle to find missing side lengths on these composite figures.
Key Concepts:
 Area is additive, meaning the area of a figure is the same as the sum of the area of nonoverlapping regions of the figure. (Lesson 1)
 It is possible to find the area of a figure by creating a new region of known or equal area. (Lesson 4)
 We can find the area of figures if we have sufficient information about the figure. We can also find unknown measurements if we know the area and sufficient information about the figure. (Lesson 8)
Prior Knowledge Needed:
 Finding area of rectangles; (Grade 04, Unit 02; 4.MD.A.3)
 Classify 2D shapes; (Grade 05, Unit 11; G.B.3, 5.G.B.4)
 Using variables to write expressions; (Grade 06, Unit 09; 6.EE.B.6)
 Solving equations for missing variables; (Grade 06, Unit 09; 6.EE.B.7)
Units on the Horizon:
 Problem solving with volume and surface area; (Grade 6, Unit 11)
 2D Figures; (Grade 7, Unit 11)
 3D Figures; (Grade 7, Unit 12)
Lessons

Lesson objective: Understand that area is additive, meaning the area of a figure is the same as the sum of the area of nonoverlapping regions of the figure. Students bring prior knowledge of finding the area of a rectangle from 4.MD.A.3. This prior kno...

Lesson objective: Decompose figures to find the total area. This lesson helps to build procedural skill with decomposing figures to find areas. Drawing a diagram is used here because it supports students’ ability to visualize the process. This work deve...

Lesson objective: Apply the method of decomposing a figure. This lesson provides an opportunity for students to apply their knowledge and understanding of decomposing figures into regions of known area to a reallife situation. Students are asked to cre...

Lesson objective: Understand that it is possible to find the area of a figure by creating a new region of known or equal area. Students bring prior knowledge of finding the area of a rectangle from 4.MD.A.3, G04_U02. This prior knowledge is extended to ...

Lesson objective: Develop and use the area formula for triangles. This lesson helps to build procedural skill with finding the area of triangles. Coordinate grids are used here because they support the students' budding understanding of geometry in the ...

Lesson objective: Develop and use the area formula for a parallelogram and trapezoid. This lesson helps to build procedural skill with finding the area of parallelograms and trapezoids. The use of coordinate grids supports students' budding understandin...

Lesson objective: Apply the formulas for finding the area of triangles, parallelograms, and trapezoids. This lesson provides an opportunity for students to apply their knowledge and understanding of finding the area of twodimensional figures to a real...

Lesson objective: Understand that we can find unknown measurements if we know the area and sufficient information about the figure. Students bring prior knowledge of finding the area from 6.G.A.1. This prior knowledge is extended to finding missing dime...

Lesson objective: Find missing lengths of sides when the area is known. This lesson helps to build procedural skill with finding missing dimensions when given the area. Solving equations is used here because it supports students’ developing algebraic sk...

Lesson objective: Apply area formulas to determine areas and to find unknown measurements. This lesson provides an opportunity for students to apply their knowledge and understanding of area formulas to a reallife situation. Students are asked to deter...