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# Reason with shapes and their attributes

## Third Grade Perspective

Students describe, analyze, and compare properties of two-dimensional shapes. They compare and classify shapes by their sides and angles, and connect these with definitions of shapes. Students also relate their fraction work to geometry by expressing the area of part of a shape as a unit fraction of a whole.

### Scaffolded Ideas

- An understanding of how shapes are described by specific attributes is key to being able to compare different shapes.
- Dividing shapes into equal shares is related to a basic understanding of fractions.

### Questions to focus instruction:

- How do students express an understanding of two-dimensional shapes?
- What are some attributes that shapes could share?
- What are quadrilaterals?
- How can parts of a shape be expressed as fractions?

### Associated Standards:

3.G.1 – Understand that shapes in different categories (e.g., rhombuses, rectangles, and others) may share attributes (e.g., having four sides), and that the shared attributes can define a larger category (e.g., quadrilaterals). Recognize rhombuses, rectangles, and squares as examples of quadrilaterals, and draw examples of quadrilaterals that do not belong to any of these subcategories.
3.G.2 – Partition shapes into parts with equal area. Express the area of each part as a unit fraction of the whole.