1. Decompose Two-Dimensional Shapes
Unit of Study: Two-Dimensional Geometry
Global Concept Guide: 3 of 4

2. Content Development
Pattern blocks are excellent tools for students to use as they analyze composite shapes. Students can place the pattern block directly on the composite shape and turn it, flip it, or slide it to fit inside the composite shape.
Students may first try to fit every pattern block within a composite shape. As they become more familiar with the relationships, children will choose specific pattern blocks to develop their answer.

3. Day 1 Essential Question: How can you identify shapes in other shapes?
Go Math Lesson 12.6, p. 505 Listen and Draw requires that students use 1 hexagon and 2 triangles to make a new shape. Encourage students to make as many different shapes as possible in minutes. Students may begin to make the same shape but different orientation—observe students and make note of this. After time, call students who have the same shape but different orientations to share them. Ask “Are these different shapes?” “Could they be the same shape?” “Why”
With partners, students will complete p. 508 Problem Solving use pattern blocks to build the composite shape shown and discuss the number of blocks used.
Students will independently use pattern blocks and p. 507 On Your Own to dissect composite shapes.
By the end of Day 1, students will be able to identify shapes in other shapes.

4. Day 2
Essential Question: How can you decompose two-dimensional shapes?
Today’s exploration will utilize paper shapes (More Two-Dimensional Shapes) that students will fold and cut into smaller shapes. Have students predict what shapes could be made before cutting. Compare student solutions.
Go Math Lesson 12.7, On Your Own, p. 511 provides students with an opportunity to transfer from hands-on manipulation of shapes to drawing possible “cut lines” to show shape parts. Use Math Talk in Action p. 511 to guide class discussion.
Tangram Puzzles encourage students to try numerous strategies for decomposing composite shapes
Tangram puzzles provide a quick opportunity for tiered differentiation: try giving more complex puzzles to those students ready for enrichment, while allowing students requiring intervention to work on simple composite shapes
The Super Source Books also provide many ideas for different Tangram pattern puzzle
By the end of Day 2, students will be able to make conjectures about and decompose two-dimensional shapes.

5. Day 3
Essential Question: How can you decompose shapes without manipulatives?
Teacher Read-Aloud: Three Pigs, One Wolf, and Seven Magic Shapes (Book is available on CyberCatfor the sake of time do not read the entire book, rather focus on important pieces of the text so that students have time to work with partners on decomposing shapes.
Students will use provided shape outlines to determine what smaller shapes could be used to make the larger shape.

6. Enrich/Reteach/Intervention
Give students increasingly challenging Tangram Puzzles
Challenge students to create more than one (or two) way to decompose a puzzle and record solutions in their journal
Intervention/Small Group:
Provide students with less challenging tangram puzzles
Reteach 12.6 (p. R96)
Tier 2 small group intervention activity (TE p. 505B)
Tier 2 small group intervention activity (TE p. 509B)

7. Literature for your Classroom Library