Kindergarten · Geometry
K.G.B.4: Analyze and compare 2D and 3D shapes
K.G.B.4 is a kindergarten 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
Analyze and compare two- and three-dimensional shapes, in different sizes and orientations, using informal language to describe their similarities, differences, parts (e.g., number of sides and vertices/"corners") and other attributes (e.g., having sides of equal length).
In plain words
Analyze and compare 2D and 3D 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
How is a triangle different from a square?
- It has 3 sides
- It has 4 sides
- It is round
Where students can get stuck
- Counting one side twice, or losing track of where they started, and saying a square has 5 sides.
- Thinking a rectangle and a square have nothing in common, not noticing both have 4 sides and 4 corners.
- Describing shapes only by color or size, saying "the red one is bigger" instead of naming sides or corners.
Effective teaching strategies
- Have students run a finger along each side of a square cutout, starting at a crayon dot, and count 4 sides and 4 corners.
- Place a square and a long rectangle side by side and ask what is the same and what is different, so students find both have 4 sides and 4 corners but only the square has equal sides.
- Challenge students to describe a hidden shape using only sides and corners, such as “three straight sides and three corners,” and have a partner guess it.
Units that teach this standard
Find where K.G.B.4 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 Math
Eureka Math²
Everyday Mathematics
Go Math!
i-Ready Classroom Mathematics
Illustrative Mathematics
Math Expressions
Don’t see your curriculum? Contact Bobby and we’ll see if we can help!
Share it with families
Families can read Comparing shapes by their sides and corners 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.