Lesson objective: Apply students' knowledge of 2D and 3D shapes to identify 2D and 3D shapes as flat or solid.

This lesson provides an opportunity for students to apply their knowledge and understanding of 2D and 3D shapes to a real-life situation. Students are asked to help Dev figure out what gift is inside the present based on the present being flat or solid.

Key Concept students will use:

- 2D and 3D shapes can be identified and described as flat or solid.

Skills students will use:

- Objects can be compared based on an attribute they share. (Grade K, Unit 8, K.MD.A.2)
- Shapes have names that are based on their attributes, and three of these shapes are squares, circles, and triangles. (Grade K. Unit 5, K.G.A.1)

Students engage in Mathematical Practice 3: Construct viable arguments and critique the reasoning of others. Mathematically proficient students will be able to apply their understandings of defining attributes to construct and critique sorting rules for shapes as they explore how to determine if a shape is flat or solid.

**Key vocabulary: **

**Special materials needed:**

- 2D shapes (pattern blocks, attribute blocks, etc.)
- 3D shapes