Students explore measurements of geometric figures in two-and three-dimensions, finding area, surface area, and volume in mathematical and real-world problems.

Unit Summary

In Unit 7, sixth graders explore measurements in geometric space in both two-dimensional and three-dimensional figures. Throughout previous grade levels, students have been composing and decomposing geometric figures. In sixth grade, students apply those concepts of composition and decomposition to new and familiar shapes to formulate properties and formulas for finding area (MP.7). By understanding the area of rectangular arrays and using regularity in repeated reasoning, students are able to determine the area of parallelograms, triangles, and other polygons that are formed from these shapes (MP.8). Students also re-engage in major work of the grade in a few ways. They use their knowledge of the coordinate plane and absolute value to represent and measure polygons in a four-quadrant plane, they write equations to represent volume of rectangular prisms with fractional side lengths, and they write and evaluate numerical expressions to represent the surface area of prisms and pyramids.

In fifth grade, students explored volume as a measurement of a three-dimensional solid with whole-number side lengths. In this unit, students will reinvestigate how to find volume when packing solids now with fractional unit cubes. They will rely on their skills of working with fractions from fifth grade and earlier in their sixth-grade year. 

Throughout the geometry standards in sixth grade through eighth grade, students will encounter increasingly complex and multi-part geometric measurement problems, culminating in eighth grade with standard 8.G.9. Learning how to make sense of these complex problems, determine solution pathways, and organize information will be important skills for students to have as the demands and rigor levels increase (MP.1).

Pacing: 19 instructional days (17 lessons, 1 flex day, 1 assessment day)

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Summer Packets

Packet of problems designed to help prepare students for the start of next school year.


This assessment accompanies Unit 7 and should be given on the suggested assessment day or after completing the unit.

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Expanded Assessment Package

Additional assessment tools to help you monitor student learning and identify any skill or knowledge gaps.

Learn how to use these tools with our Guide to Assessments


Unit Prep

Essential Understandings


  • The area of any triangle is half the area of a rectangle with the same base and height: $${A={1\over2}bh}$$.
  • The area of polygons can be found by decomposing the polygon into familiar shapes or by building around the polygon and subtracting the extra area.
  • The volume of a prism with fractional side lengths is equal to the number of fractional unit cubes it takes to fill the prism multiplied by the volume of one fractional unit cube. The volume of any rectangular prism can be found by multiplying the length, width, and height.
  • A three-dimensional figure can be represented by a two-dimensional net; nets are valuable tools in understanding and determining the surface area of three-dimensional figures.





right triangle







acute triangle

obtuse triangle


unit cube







surface area


Related Teacher Tools:

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Vocabulary Package

Additional vocabulary tools that help reinforce and support student vocabulary development.

Unit Materials, Representations and Tools


  • Graph paper
  • Three-dimensional solids and foldable nets
  • Calculators 
  • Template: Nets
  • Geoboards

Intellectual Prep


Internalization of Standards via the Unit Assessment

  • Take unit assessment. Annotate for: 
    • Standards that each question aligns to
    • Strategies and representations used in daily lessons
    • Relationship to Essential Understandings of unit 
    • Lesson(s) that assessment points to

Internalization of Trajectory of Unit

  • Read and annotate “Unit Summary”
  • Notice the progression of concepts through the unit using “Unit at a Glance”
  • Do all target tasks. Annotate the target tasks for: 
    • Essential understandings
    • Connection to assessment questions
  • Identify key opportunities to engage students in academic discourse. Read through our Guide to Academic Discourse and refer back to it throughout the unit.

Unit-Specific Intellectual Prep

Lesson Map

Topic A: Area of Triangles, Quadrilaterals, and Polygons

Topic B: Polygons in the Coordinate Plane

Topic C: Volume of Rectangular Prisms

Topic D: Nets and Surface Area

Common Core Standards

Key: Major Cluster Supporting Cluster Additional Cluster

Core Standards


  • 6.G.A.1 — Find the area of right triangles, other triangles, special quadrilaterals, and polygons by composing into rectangles or decomposing into triangles and other shapes; apply these techniques in the context of solving real-world and mathematical problems.

  • 6.G.A.2 — Find the volume of a right rectangular prism with fractional edge lengths by packing it with unit cubes of the appropriate unit fraction edge lengths, and show that the volume is the same as would be found by multiplying the edge lengths of the prism. Apply the formulas V = l w h and V = b h to find volumes of right rectangular prisms with fractional edge lengths in the context of solving real-world and mathematical problems.

  • 6.G.A.3 — Draw polygons in the coordinate plane given coordinates for the vertices; use coordinates to find the length of a side joining points with the same first coordinate or the same second coordinate. Apply these techniques in the context of solving real-world and mathematical problems.

  • 6.G.A.4 — Represent three-dimensional figures using nets made up of rectangles and triangles, and use the nets to find the surface area of these figures. Apply these techniques in the context of solving real-world and mathematical problems.

Foundational Standards


Expressions and Equations
  • 6.EE.A.1

  • 6.EE.B.7

Measurement and Data
  • 3.MD.C.7

  • 3.MD.C.7.D

  • 4.MD.A.3

  • 5.MD.C.5

  • 5.MD.C.5.B

  • 5.MD.C.5.C

Number and Operations—Fractions
  • 5.NF.B.4

  • 5.NF.B.6

The Number System
  • 6.NS.A.1

  • 6.NS.C.6

Future Standards


  • 7.G.A.1

  • 7.G.A.2

  • 7.G.A.3

  • 7.G.B.4

  • 7.G.B.5

  • 7.G.B.6

  • 8.G.C.9

Standards for Mathematical Practice

  • CCSS.MATH.PRACTICE.MP1 — Make sense of problems and persevere in solving them.

  • CCSS.MATH.PRACTICE.MP2 — Reason abstractly and quantitatively.

  • CCSS.MATH.PRACTICE.MP3 — Construct viable arguments and critique the reasoning of others.

  • CCSS.MATH.PRACTICE.MP4 — Model with mathematics.

  • CCSS.MATH.PRACTICE.MP5 — Use appropriate tools strategically.

  • CCSS.MATH.PRACTICE.MP6 — Attend to precision.

  • CCSS.MATH.PRACTICE.MP7 — Look for and make use of structure.

  • CCSS.MATH.PRACTICE.MP8 — Look for and express regularity in repeated reasoning.