3rd Grade · Geometry
3.G.A.2: Split shapes into equal parts, and name each part as a fraction
3.G.A.2 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
Partition shapes into parts with equal areas. Express the area of each part as a unit fraction of the whole. For example, partition a shape into 4 parts with equal area, and describe the area of each part as 1/4 of the area of the shape.
In plain words
Split shapes into equal parts, and name each part as a fraction.
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
A pizza is cut into 8 equal slices. What fraction represents one slice of the pizza?
- 1/4
- 8
- 1/8
Where students can get stuck
- Splitting a shape into parts of different sizes and still calling each part 1/4, because there are four of them.
- Thinking equal parts must look alike, so two differently shaped halves with the same area do not count.
- Writing the number of parts instead of a fraction, such as 4 instead of 1/4.
Effective teaching strategies
- Fold paper shapes into equal parts and ask students to prove the parts are equal by laying them on top of each other.
- Show two copies of the same square, one folded into two rectangles and one folded along the diagonal into two triangles, and ask whether the halves are equal, discussing area.
- Have students name each equal part as a unit fraction, such as 1/4, and say what the 4 and the 1 each tell.
Units that teach this standard
Find where 3.G.A.2 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
i-Ready Classroom Mathematics
Illustrative Mathematics
Zearn Math
Don’t see your curriculum? Contact Bobby and we’ll see if we can help!
Share it with families
Families can read Splitting shapes into equal parts 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
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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.