Virginia SOL 3.MG.4.b
The Standard
Classify figures as polygons or not polygons and justify reasoning.
Virginia Standards of Learning for Mathematics · The student will identify, describe, classify, compare, combine, and subdivide polygons.
Teacher's field guide
What This Standard Means
What Students Need to Do
- Students inspect each plane figure for straight sides and a fully closed boundary. They decide whether it belongs in the polygon group and explain their decision using those features.
What Mastery Looks Like
- Students correctly sort familiar and unfamiliar figures, including rotated and irregular examples. They justify each choice by checking for a closed shape made only of straight line segments.
Common Misconceptions
- Students may count any familiar shape even when it has a gap or a curved side. They may think only regular, upright shapes qualify. Some justify choices by saying a figure “looks right” instead of naming its attributes.
How to Assess It
- Exit ticket: show a closed five-sided figure, an open four-sided figure, and a closed figure with one curved side. Students label each and write one reason.
Lesson moves
Ways to Teach It
Give pairs craft sticks and clay, have them build closed shapes, then alter one feature to make each shape fail the polygon test.
Show a triangle, an open pentagon, and a curved shape, then ask students to defend which figures pass the polygon test.
Play Polygon Detective: reveal one figure card at a time, and award a point only when the claim includes a defining attribute.
Photograph classroom signs and objects, then label which flat outlines are polygons and explain why a circular clock face is not.
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Printable 3.MG.4.b Worksheet
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Related Standards
- 6.MG.4.a
Identify regular polygons.
- 3.MG.4
The student will identify, describe, classify, compare, combine, and subdivide polygons.
- 5.MG.3.b
Classify triangles as right, acute, or obtuse and equilateral, scalene, or isosceles and justify reasoning.
- 3.MG.4.e
Classify and compare polygons (triangles, quadrilaterals, pentagons, hexagons, octagons).
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