1st Grade · Geometry
1.G.A.3: Partition circles and rectangles into two and four equal shares
1.G.A.3 is a 1st 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 and four equal shares, describe the shares using the words halves, fourths, and quarters, and use the phrases half of, fourth of, and quarter of. Describe the whole as two of, or four of the shares. Understand for these examples that decomposing into more equal shares creates smaller shares.
In plain words
Partition circles and rectangles into two and 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
You baked a square cake and cut it into quarters. If you have four pieces of the cake, and each piece is a quarter, how many whole cakes do you have?
- 4
- 2
- 1
Where students can get stuck
- Calling any two pieces halves, even when one is clearly bigger, because halves seem to mean two parts, not two equal parts.
- Believing a fourth is bigger than a half because four is bigger than two.
- Cutting a rectangle into four unequal pieces and still calling each one a fourth.
Effective teaching strategies
- Fold a paper rectangle into two parts so the edges match exactly, and have students check that both halves are the same size by laying one on the other.
- Split each half in half again to make fourths, then lay a fourth on a half and ask which is smaller, so students see that more shares means smaller shares.
- Draw a rectangle cut into four unequal pieces and ask whether each piece is a fourth, then have students explain why the pieces must match in size.
Units that teach this standard
Find where 1.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
Everyday Mathematics
i-Ready Classroom Mathematics
Illustrative Mathematics
Into Math
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 and quarters of circles and rectangles 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.