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.
Official wording from the Common Core State Standards for Mathematics (Β© 2010 National Governors Association Center for Best Practices and Council of Chief State School Officers). View on thecorestandards.org
Shapes belong to families defined by their attributes. Every shape with four straight sides is a quadrilateral, whether it is a square, a rectangle, a rhombus or a lopsided four-sided figure with no special features at all. Third graders learn that shapes in different categories can share attributes, and that a shared attribute like having four sides is exactly what defines the larger category.
Students sort and describe shapes using properties such as the number of sides, the number of angles, whether sides are equal in length and whether angles are right angles. A rhombus has four equal sides, a rectangle has four right angles, and a square has both, which means a square is a special rhombus and also a special rectangle. Students also draw quadrilaterals that are none of these, such as a kite or a shape with all different sides, to show that the quadrilateral family is bigger than its best-known members. Reasoning about categories this way is early logical thinking about "all" and "some" statements.
Students often say squares and rectangles are completely different. Check the rectangle definition (four sides, four right angles): a square meets it.
A square turned on its corner may be called a diamond and treated as a new shape. Rotate cut-out shapes to show attributes stay the same.
Children may not accept an irregular four-sided shape as a quadrilateral. Stress that any closed shape with four straight sides belongs.
Shapes that look "long" are called rectangles even without right angles. Use corner checkers (a folded paper corner) to test angles.
Use attributes to decide whether a square is a rhombus, and draw a quadrilateral that is neither.
Answer: Yes, a square is a rhombus (and a rectangle). A four-sided shape with unequal sides and no right angles is a quadrilateral that is none of these.
Shape sorts with Venn diagrams work well: label circles "4 equal sides" and "4 right angles" and watch squares land in the overlap. Ask students to draw a shape for each region, including the outside region of quadrilaterals with neither property.
Assessment items ask students to select all the shapes that are quadrilaterals, choose which statement is true about squares and rectangles, or draw a quadrilateral that does not belong to a named group.
Original questions written for this standard. Choose an option or type your answer, then press Check. Every question has a worked explanation.
Answer: C) Four sides
A quadrilateral is any closed shape with four straight sides. The other attributes only apply to some quadrilaterals.
Answer: B) Every square is a rectangle.
A square has four sides and four right angles, which is the definition of a rectangle. Not every rectangle has four equal sides.
Answer: 4 (also accepted: four)
A rectangle has four right angles.
Answer: D) A rhombus
Four equal sides makes it a rhombus. Without right angles it is not a square or a rectangle.
Answer: C) A shape with 4 sides of different lengths and no right angles
A four-sided shape with unequal sides and no right angles is a quadrilateral that belongs to none of the special categories.
Answer: 4 (also accepted: four)
Quad means four: every quadrilateral has exactly four sides.
Recognize and draw shapes having specified attributes, such as a given number of angles or a given number of equal faces. Identify triangles, quadrilaterals, pentagons, hexagons, and cubes.
Distinguish between defining attributes (e.g., triangles are closed and three-sided) versus non-defining attributes (e.g., color, orientation, overall size); build and draw shapes to possess defining attributes.
A full lesson with slides, activities and an exit ticket on classifying quadrilaterals by attributes, pitched to grade 3 and editable in PowerPoint or Google Slides.
Make a lesson βA printable, differentiated worksheet on 3.G.A.1 with an answer key, ready in about a minute.
Make a worksheet βTurn classifying quadrilaterals by attributes into a quiz students answer online that marks itself, with a class summary for you.
Build a test βThe standard names rhombuses, rectangles and squares. Other quadrilaterals may come up, and fuller classification by parallel sides comes in 4.G.A.2 and 5.G.B.3.
It teaches students that categories are defined by attributes, not by how a shape looks. That reasoning underpins later geometry and logic.