Lesson objective: Understand that we use what we know about the defining attributes of shapes to build shapes with materials.

Students bring prior knowledge of defining attributes from K.G.A.1 and K.G.A.2. This prior knowledge is extended to building shapes as students use materials to make concrete representations of shapes. A conceptual challenge students may encounter is applying their knowledge of all the defining attributes for each shape.

The concept is developed through work with straws and clay, which provide the concrete materials needed to make the sides and corners of shapes ( circles, triangles, squares, rectangles and hexagons).

This work helps students deepen their understanding of operations because students will add and subtract materials as they build the sides and corners of shapes.

Students engage in Mathematical Practice 2 (Reason abstractly and quantitatively) as they visualize the defining attributes and apply their understandings to build the shapes with the materials provided.

Students also engage in Mathematical Practice #7 (Look for and make use of structure) as they apply their understandings of the structure of shapes to build each shape.

**Key vocabulary:**

**Special materials needed:**