Lesson plan

# 1. Understand that shapes have defining and non-defining attributes (C)

teaches Common Core State Standards CCSS.Math.Content.1.G.A.1 http://corestandards.org/Math/Content/1/G/A/1
teaches Common Core State Standards CCSS.Math.Practice.MP2 http://corestandards.org/Math/Practice/MP2

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Lesson objective: Understand that all shapes have defining attributes that cannot change because they name the shape, as well as non-defining attributes that can change without changing the shape.

Students bring prior knowledge of comparing and analyzing 2- and 3-dimensional shapes in different sizes and orientations, as well as defining attributes of circles and squares from K.G.B.4. This prior knowledge is extended to include additional shapes like triangles, rectangles, and trapezoids as students sort different shapes by their defining and non-defining attributes. A conceptual challenge students may encounter is confusing defining and non-defining attributes.

The concept is developed through work with pattern blocks, shape cut-outs, or tangrams, which allow students to physically demonstrate their reasoning by manipulating shapes..

This work helps students deepen their understanding of numbers because shapes can be defined by attributes such as the number of sides, angles, faces, or edges.

Students engage in Mathematical Practice 2 (reason abstractly and quantitatively) as they make sense of the relationships between defining and non-defining attributes of shapes.

Key vocabulary:

• attribute
• defining attributes
• non-defining attributes

Special materials needed:

• pattern blocks
• shape cut-outs
• tangrams