3rd Grade · Geometry
3.G.A.1: Sort shapes into groups, like quadrilaterals (four-sided shapes)
3.G.A.1 is a 3rd grade Common Core math standard in Geometry. Here’s what it really covers, and how you can help your students learn it.
By Robert “Bobby” BarnettMath teacher, parent, and founder of Bobby’s Math Club
The standard
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.
In plain words
Sort shapes into groups, like quadrilaterals (four-sided shapes).
Sample questions from student practice
These questions from Bobby's Math Club are the kinds of questions your students will see. You can try answering them to see what a student might see.
Question 1 of 3
Look at the shapes. They are all quadrilaterals. How many of them have 4 square corners?
- 2
- 3
- 1
Where students can get stuck
- Saying a square is not a rectangle because it does not look long and thin, though it has four square corners.
- Thinking a turned shape becomes a different shape, calling a tilted square a diamond instead of a square.
- Counting only rectangles and squares as quadrilaterals, leaving out shapes with four uneven straight sides.
Effective teaching strategies
- Sort shape cards by attributes such as the number of sides and square corners, and ask which groups a square belongs in and why.
- Turn a square in different directions and ask whether it is still a square, so students see that turning does not change a shape.
- Ask students to draw a quadrilateral that is not a rectangle, rhombus, or square, and explain why it still belongs.
Units that teach this standard
Find where 3.G.A.1 lands in the program you teach. Each unit has a guide written for families. Unit names and order vary between editions and districts, so your school’s own materials have the exact sequence.
Bridges in Mathematics
enVision Mathematics
Everyday Mathematics
i-Ready Classroom Mathematics
Illustrative Mathematics
Math Expressions
Reveal Math
Don’t see your curriculum? Contact Bobby and we’ll see if we can help!
Share it with families
Families can read Sorting four-sided shapes into families for a plain-language look at this skill, with three questions to try together and ideas for helping at home.
Help every student practice geometry at home
In Bobby's Math Club, students practice at just the right level, with a hint when they need one, a clear explanation after every question, and kid-friendly videos. Unlimited practice is free for every family.
See how it works for teachers
Written by Robert “Bobby” Barnett
Bobby is an award-winning math teacher, the author of Meet Every Learner’s Needs, and the father of two elementary-school math learners. He uses Bobby’s Math Club with his own kids a few times every week. Learn more or contact Bobby.