Comparison of 2D Shapes and 3D Objects
Warm-up
Mystery shape: describe a shape using only attribute language, no name. I have 4 sides. All sides are the same length. All corners are the same. What am I? (Square.) I have 4 sides. Two long, two short. What could I be? (Rectangle.) Students love guessing, and guessing requires attribute reasoning.
Explore
Tangram challenge: use all 7 pieces to fill a given silhouette. Then: choose 3 pieces and record what shapes you can make. Name each composite shape. I made a rectangle using a square and two small triangles.
Consolidate
Practice
Students sort a collection two different ways with different attributes, draw each sort, and write their rule. Exit ticket: teacher holds up a shape and student writes one attribute that could be used to sort it.
Exit ticket
Students sort a collection two different ways with different attributes, draw each sort, and write their rule. Exit ticket: teacher holds up a shape and student writes one attribute that could be used to sort it.
A circle is entirely curved. A square has all straight sides. They should be in different groups. Ask: does a square have any curved parts? Careful examination leads to self-correction.
Ask each to explain their rule. If both rules are consistently applied, both sorts are valid: they used different attributes. Celebrate: the same shape can belong in different groups depending on your sorting rule.