2nd Grade · Geometry
2.G.A.3: Partition circles and rectangles into two, three, or four equal shares
2.G.A.3 is a 2nd 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
Partition circles and rectangles into two, three, or four equal shares, describe the shares using the words halves, thirds, half of, a third of, etc., and describe the whole as two halves, three thirds, four fourths. Recognize that equal shares of identical wholes need not have the same shape.
In plain words
Partition circles and rectangles into two, three, or four equal shares.
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
How many fourths does it take to make one whole shape?
- Two
- Three
- Four
Where students can get stuck
- Calling any three pieces thirds, even when they are clearly different sizes.
- Believing two halves cut different ways cannot both be halves, such as a triangle half and a rectangle half of a square.
- Thinking a third is bigger than a half because 3 is bigger than 2.
Effective teaching strategies
- Fold paper rectangles into halves, thirds, and fourths and circles into halves and fourths, and have students prove the shares are equal by laying one on top of another.
- Show a square cut into halves two ways, down the middle and along the diagonal, so students see that equal shares of the same whole can have different shapes.
- Compare two same-size paper rectangles folded into halves and thirds, and ask which share is bigger, so students see that more equal shares make each share smaller.
Units that teach this standard
Find where 2.G.A.3 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
Eureka Math²
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 Halves, thirds, and fourths of shapes 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.