Lesson objective: Apply the method of decomposing a figure.
This lesson provides an opportunity for students to apply their knowledge and understanding of decomposing figures into regions of known area to a reallife situation. Students are asked to create a pattern for a pool sidewalk and determine the area that will be covered by each color and the cost for their design.
Key Concept students will use:

Area is additive, meaning the area of a figure is the same as the sum of the area of nonoverlapping regions of the figure.
Skills students will use:
 finding the area of a rectangle (Grade 4, Unit 2).
 decomposing a figure into rectangles.
Students engage in Mathematical Practice 2 (Reason Abstractly and Quantitatively) as they determine which color blocks will provide a pleasing design and keep the cost of the project down.
Key vocabulary:
 area
 decompose
Special materials needed:
 Graph paper may be helpful for some students.