In the first grade lessons, students continue their study of shapes by learning to recognize parallel lines, parallelograms, trapezoids, half-circles, and quarter-circles. Defining attributes are distinguished from other attributes, and students draw shapes that possess given defining features. They compose both two- and three-dimensional shapes to form new shapes. They partition circles and rectangles into two and four equal shares and begin their introduction to the language of fractions by using the terms *half, fourth, and quarter.*

- CCSS.MATH.CONTENT.1.G.A.1
- CCSS.MATH.PRACTICE.MP3
- CCSS.MATH.PRACTICE.MP4

- Basic Shapes: Triangles
- Basic Shapes: Polygons

- CCSS.MATH.CONTENT.1.G.A.1
- CCSS.MATH.PRACTICE.MP3
- CCSS.MATH.PRACTICE.MP7

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

- CCSS.MATH.CONTENT.1.G.A.1
- CCSS.MATH.PRACTICE.MP3
- CCSS.MATH.PRACTICE.MP7

- Basic Shapes: Polygons
- Basic Shapes: Quadrilaterals
- Basic Shapes: Triangles
- Composing Polygons

- CCSS.MATH.CONTENT.1.G.A.1
- CCSS.MATH.PRACTICE.MP3
- CCSS.MATH.PRACTICE.MP7

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

- CCSS.MATH.CONTENT.1.G.A.1
- CCSS.MATH.PRACTICE.MP3
- CCSS.MATH.PRACTICE.MP4

- Basic Shapes: Quadrilaterals
- Composing Polygons (optional)
- Geometry Sticks: Customary (optional)
- Geometry Sticks: Metric (optional)
- Parallel Line Tester

- CCSS.MATH.CONTENT.1.G.A.1
- CCSS.MATH.PRACTICE.MP3
- CCSS.MATH.PRACTICE.MP7

- Angle Tester
- Basic Shapes: Circles
- Basic Shapes: Polygons
- Basic Shapes: Quadrilaterals
- Basic Shapes: Triangles
- Composing Polygons

- CCSS.MATH.CONTENT.1.G.A.2
- CCSS.MATH.CONTENT.1.G.A.3
- CCSS.MATH.PRACTICE.MP3
- CCSS.MATH.PRACTICE.MP4

- Adjustable Angle (optional)
- Basic Shapes: Circles
- Partitioning Circles

Students sort two-dimensional shapes based on their defining attributes.

- CCSS.MATH.CONTENT.1.G.A.1
- CCSS.MATH.PRACTICE.MP3
- CCSS.MATH.PRACTICE.MP4

- Basic Shapes: Circles
- Basic Shapes: Polygons
- Basic Shapes: Quadrilaterals
- Basic Shapes: Triangles

- CCSS.MATH.CONTENT.1.G.A.2
- CCSS.MATH.PRACTICE.MP3
- CCSS.MATH.PRACTICE.MP4

- Basic Shapes: Circles
- Basic Shapes: Polygons
- Basic Shapes: Quadrilaterals
- Basic Shapes: Triangles

- CCSS.MATH.CONTENT.1.G.A.2
- CCSS.MATH.PRACTICE.MP3
- CCSS.MATH.PRACTICE.MP4

- Decomposing Shapes
- Tangram

- CCSS.MATH.CONTENT.1.G.A.1
- CCSS.MATH.PRACTICE.MP3
- CCSS.MATH.PRACTICE.MP7

- Basic Shapes: Circles
- Basic Shapes: Quadrilaterals
- Basic Shapes: Right Solids

- CCSS.MATH.CONTENT.1.G.A.2
- CCSS.MATH.PRACTICE.MP3
- CCSS.MATH.PRACTICE.MP4

- Basic Shapes: Polygons
- Basic Shapes: Right Solids
- Composing Polyhedrons (optional)

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

- Partitioning Circles

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

- Partitioning Rectangles

**The Grade 1 lessons address the fourth critical area of focus in the geometry domain of the Common Core State Standards (CCSS):**

Students compose and decompose plane or solid figures (e.g., put two triangles together to make a quadrilateral) and build understanding of part-whole relationships as well as the properties of the original and composite shapes. As they combine shapes, they recognize them from different perspectives and orientations, describe their geometric attributes, and determine how they are alike and different, to develop the background for measurement and for initial understandings of properties such as congruence and symmetry (CCSS, 2010, p. 13).