In the third grade lessons, students focus on shared attributes of shapes and further refine their understanding of the relationships among shape categories. They enlarge their understanding of the quadrilateral category with an introduction to rhombuses, kites, and deltoids. They classify squares, rectangles, trapezoids, parallelograms, kites, deltoids, rhombuses, and other four-sided closed shapes as quadrilaterals. They partition shapes into parts with equal areas and express the area of each part as a fraction of the whole.

- CCSS.MATH.CONTENT.3.G.A.1
- CCSS.MATH.PRACTICE.MP2
- CCSS.MATH.PRACTICE.MP7

- Angle Tester
- Basic Shapes: Circles
- Basic Shapes: Polygons
- Basic Shapes: Quadrilaterals
- Basic Shapes: Triangles
- Composing Polygons (optional)
- Parallel Line Tester
- Partitioning Circles

- CCSS.MATH.CONTENT.3.G.A.1
- CCSS.MATH.PRACTICE.MP2
- CCSS.MATH.PRACTICE.MP7

- Angle Tester
- Basic Shapes: Quadrilaterals
- Parallel Line Tester

- CCSS.MATH.CONTENT.3.G.A.1
- CCSS.MATH.PRACTICE.MP2
- CCSS.MATH.PRACTICE.MP7

- Basic Shapes: Quadrilaterals
- Parallel Line Tester

- CCSS.MATH.CONTENT.3.G.A.1
- CCSS.MATH.PRACTICE.MP2
- CCSS.MATH.PRACTICE.MP7

- Basic Shapes: Polygons
- Basic Shapes: Quadrilaterals

- CCSS.MATH.CONTENT.3.G.A.1
- CCSS.MATH.PRACTICE.MP2
- CCSS.MATH.PRACTICE.MP7

- Basic Shapes: Quadrilaterals

- CCSS.MATH.CONTENT.3.G.A.2
- CCSS.MATH.CONTENT.3.MD.C.5.A
- CCSS.MATH.CONTENT.3.MD.C.5.B
- CCSS.MATH.CONTENT.3.MD.C.6
- CCSS.MATH.PRACTICE.MP2
- CCSS.MATH.PRACTICE.MP8

- Partitioning Rectangles

- CCSS.MATH.CONTENT.3.G.A.2
- CCSS.MATH.PRACTICE.MP2
- CCSS.MATH.PRACTICE.MP7

- Decomposing Shapes
- Basic Shapes: Polygons (optional)
- Basic Shapes: Triangles (optional)
- Basic Shapes: Quadrilaterals (optional)
- Partitioning Rectangles (optional)

**The Grade 3 lessons address the fourth critical area of focus in the geometry domain of the Common Core State Standards (CCSS):**

Students describe, analyze, and compare properties of two-dimensional shapes. They compare and classify shapes by their sides and angles, and connect these with definitions of shapes. Students also relate their fraction work to geometry by expressing the area of part of a shape as a unit fraction of the whole (CCSS, 2010, p. 21).