Lesson objective: Identify and name regular and irregular shapes.

This lesson provides an opportunity for students to apply their knowledge and understanding of defining characteristics to a mathematical situation. Students are asked to design two sets each of five buttons, where each set shares defining attributes but does not contain identical shapes.

Key Concept students will use:

- Certain shapes (triangles, quadrilaterals, pentagons, hexagons, and cubes) are defined by their sides and angles.

Skills students will use:

- knowledge of defining attributes (Grade 1, Unit 7)
- ability to count sides and angles in a given shape

Students engage in Mathematical Practice 2 (Reason abstractly and quantitatively) as they draw irregular shapes that share defining characteristics.

**Key vocabulary: **

- angle
- hexagon
- pentagon
- quadrilateral
- side
- triangle