3rd Grade Math Lesson

Stained-Glass Shape Detectives: Classifying Quadrilaterals by Attributes

Shared by A STEM Educator

3rd GradeBTC Vertical Whiteboard Framing3.G.A.150 min

Learning Objective

Students will classify two-dimensional shapes — with emphasis on quadrilaterals — by their defining attributes (number of sides, parallel sides, right angles, equal side lengths), and recognize that shapes can belong to multiple categories simultaneously (e.g., a square is also a rectangle and a parallelogram).

Lesson Overview

Students move from identifying basic polygons by side count to classifying quadrilaterals into a hierarchical structure using defining attributes (side lengths, parallel sides, right angles), set in the context of designing stained-glass window panels.

Materials

Vertical whiteboards or large chart paper (one per group of 3)
Dry-erase markers in multiple colors
Random grouping cards
Printed shape card sets (triangles, quadrilaterals, pentagons, hexagons in varied orientations)
Rulers and right-angle corner cards
Class anchor chart: Quadrilateral Attribute Table (blank, to fill during consolidation)

Scaffolded Task Progression

1Task 1

A stained-glass artist has a pile of glass pieces. Sort the shapes below into two groups: Quadrilaterals and Not Quadrilaterals. Write each shape name in the correct column on your board. Shapes: triangle, rectangle, pentagon, square, hexagon, rhombus, trapezoid, octagon.

[ Interactive graph / diagram — available in the full lesson ]

2Task 2

The artist now needs to check which glass panels have right angles (square corners). Look at the four quadrilateral panels below. On your board, mark each shape with a small square in each corner that IS a right angle. Then write: which shapes have all four right angles?

[ Interactive graph / diagram — available in the full lesson ]

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