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K–12 teaching and learning · from the UNC School of Education

Investigating the concept of triangle and properties of polygons

http://www.nctm.org/standards/content.aspx?menu_id=1155&id=26867

A lesson plan for grades K–2 Mathematics

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This two-part example from Illuminations describes activities using interactive geoboards to help students identify simple geometric shapes, describe their properties, and develop spatial sense. This first part, Making Triangles, focuses attention on the concept of triangle, helping students understand the mathematical meaning of a triangle and the idea of congruence, or sameness, in geometry. In the next part, Creating Polygons, students make and compare a variety of polygons, describing the salient properties of the shapes they create.

E-Math Investigations are selected e-examples from the electronic version of the Principles and Standards of School Mathematics (PSSM). The e-examples are part of the electronic version of the PSSM document. Given their interactive nature and focused discussion tied to the PSSM document, the e-examples are natural companions to the i-Math investigations.

North Carolina Curriculum Alignment

Mathematics (2004)

Grade 1

  • Goal 3: Geometry - The learner will identify, describe, draw, and build basic geometric figures.
    • Objective 3.01: Identify, build, draw and name parallelograms, squares, trapezoids, and hexagons.
    • Objective 3.03: Compare and contrast geometric figures.

Grade 2

  • Goal 3: Geometry - The learner will perform simple transformations.
    • Objective 3.03: Identify and make:
      • Symmetric figures.
      • Congruent figures.

Kindergarten

  • Goal 3: Geometry - The learner will explore the concepts of geometry.
    • Objective 3.01: Identify, build, draw, and name triangles, rectangles, and circles; identify, build, and name spheres and cubes.
    • Objective 3.02: Compare geometric shapes (identify likenesses and differences).