## Geometry Curriculum Track In the second grade lessons, students extend their study of shapes to quadrilaterals and pentagons. They begin to recognize parallelograms, trapezoids, rectangles, and squares as special cases of quadrilaterals. They review the names and attributes of solid shapes introduced in kindergarten (cube, cone, cylinder, and sphere) and first grade (prism) and then analyze attributes of solid shapes. The foundation for the concept of area is developed by having students partition rectangles into rows and columns of same-size squares counting the number of squares into which a rectangle has been partitioned. Students observe the relationship between the size of the square into which a rectangle has been partitioned and the number of resulting squares. They partition circles and rectangles into two, three, or four equal shares and use the words halves, thirds, fourths, and quarters to describe the parts. They recognize that equal shares of two circles are the same only when they come from identical circles and that two equal shares of identical wholes need not have the same shape.

#### Lesson 1: Introducing Pentagons

This lesson begins with a review of polygons introduced in Kindergarten (triangle, rectangle, square, and hexagon) and first grade (trapezoid) in light of their defining attributes. Students then develop a working definition of a pentagon that can be used to discriminate between two-dimensional shapes that are pentagons and those that are not pentagons. Emphasis is placed on the defining attributes of pentagons.

• CCSS.MATH.CONTENT.2.G.A.1
• CCSS.MATH.PRACTICE.MP3

### MyStemKits 3D Kits Used

• Basic Shapes: Circles
• Basic Shapes: Polygons
• Basic Shapes: Triangles

#### Lesson 2: Solid Shapes

This lesson begins with a review of the names and attributes of solid shapes introduced in Kindergarten (cube, cone, cylinder, and sphere) and first grade (prism). Then students analyze attributes of solid shapes by describing the number and type of the faces and the number of vertices and edges.

• CCSS.MATH.CONTENT.2.G.A.1
• CCSS.MATH.PRACTICE.MP2

### MyStemKits 3D Kits Used

• Basic Shapes: Right Solids

Students develop a working definition of a quadrilateral that can be used to discriminate between two-dimensional shapes that are quadrilaterals and those that are not. Emphasis is placed on the defining attributes of quadrilaterals. Students reexamine parallelograms, trapezoids, rectangles, and squares as special cases of quadrilaterals.

• CCSS.MATH.CONTENT.2.G.A.1
• CCSS.MATH.PRACTICE.MP2
• CCSS.MATH.PRACTICE.MP3
• CCSS.MATH.PRACTICE.MP6

### MyStemKits 3D Kits Used

• Angle Tester
• Basic Shapes: Circles
• Basic Shapes: Polygons
• Basic Shapes: Triangles
• Parallel Line Tester

#### Lesson 4: Partitions and Equal Shares – Circles

Students partition circles into two, three, or four equal shares and use the words halves, thirds, and fourths to describe the parts. They understand that two halves, three thirds, and four fourths comprise a whole and recognize that equal shares of two circles are the same only when they come from identical circles.

• CCSS.MATH.CONTENT.2.G.A.3
• CCSS.MATH.PRACTICE.MP2

### MyStemKits 3D Kits Used

• Partitioning Circles

#### Lesson 5: Partitions and Equal Shares – Rectangles

Students partition rectangles into two, three, or four equal shares and use the words halves, thirds, and fourths to describe the parts. They understand that two halves, three thirds, and four fourths comprise a whole and recognize that equal shares of identical wholes need not have the same shape.

• CCSS.MATH.CONTENT.2.G.A.3
• CCSS.MATH.PRACTICE.MP2

### MyStemKits 3D Kits Used

• Partitioning Circles
• Partitioning Rectangles

#### Lesson 6: Partitioning Rectangles and Arrays

Students partition rectangles into rows and columns of same-size squares. They begin the development of the concept of area by counting the number of squares into which a rectangle has been partitioned. They discover that the size of the rectangle affects the number of squares in the partition as they write repeated addition sentences to describe the arrays they created.

• CCSS.MATH.CONTENT.2.G.A.2
• CCSS.MATH.CONTENT.2.OA.C.4
• CCSS.MATH.PRACTICE.MP2
• CCSS.MATH.PRACTICE.MP5

### MyStemKits 3D Kits Used

• Partitioning Rectangles

The Grade 2 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).

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