3.G.1: Sort Quadrilaterals by Their Attributes
Also written as 3.G.A.1 and CCSS.MATH.CONTENT.3.G.A.1 · Cluster: Reason with shapes and their attributes.
The Official Wording
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.
Common Core State Standards, Grade 3, Geometry · Read it at the source · Checked October 14, 2026
What 3.G.1 Means in Plain English
Third graders sort four-sided shapes by what they share. A rhombus has four equal sides, a rectangle has four right angles, and a square has both, so it belongs to both groups. All of them are quadrilaterals, and so is a kite or a lopsided shape that fits neither.
Second grade named shapes by counting sides and angles (2.G.1). Here the groups nest inside each other for the first time. In 4th grade students sort by parallel and perpendicular sides and right angles (4.G.2), and 5th grade builds the whole family tree (5.G.4).
3.G.1 I Can Statements
- I can tell what rhombuses, rectangles and squares have in common.
- I can explain why a square is also a rhombus and a rectangle.
- I can draw a quadrilateral that is not a rhombus, rectangle or square.
3.G.1 Worked Example
Five shape cards sorted by sides and corners, then one more shape drawn that fits no named group.
Sort these cards: a square, a 2 by 5 rectangle, a rhombus with slanted sides, a trapezoid with two slanted sides, and a triangle. Then draw a quadrilateral that is not a rhombus, a rectangle or a square.
- Count sides first. Four sides makes a quadrilateral, so the triangle is out.4 quadrilaterals, 1 triangle
- Measure the sides. Which cards have four equal sides?Rhombus group: the square and the rhombus
- Check the corners with the corner of an index card. Which cards have four right angles?Rectangle group: the square and the 2 by 5 rectangle
- The square turned up twice, because it has both attributes.Square: a rhombus and a rectangle
- The trapezoid has four sides, but its sides are not all equal and its corners are not square.Trapezoid: a quadrilateral only
- Draw one more like the trapezoid: four sides of different lengths, no right angles.a lopsided four-sided shape
Check it: Read each label back as a sentence: a square has four equal sides and four right angles, so both group names fit it.
Common Mistakes with 3.G.1
A square is not a rectangle
The square left out of the rectangle group because “rectangles are long”
Try this: Check the rule, not the look: four right angles makes a rectangle, and every square has four right angles.
A turned square becomes a diamond
A square tilted onto its corner called a diamond and sorted as a different shape
Try this: Turn the card slowly in front of the class. The sides and angles never change, so the name stays the same.
Only the textbook quadrilaterals
Asked for a quadrilateral that is none of the three, the student draws a triangle or says there is none
Try this: Have students draw four dots anywhere and join them around without crossing lines. Almost every result fits no named group.
Where 3.G.1 Fits
Practice 3.G.1
Quick Check
- What do a rhombus, a rectangle and a square all have in common?
- Is a square a rhombus? Why?
- A shape has four sides of different lengths and no right angles. What is it?