Bridges in Mathematics Kindergarten, Unit 5: Two-Dimensional Geometry
In this unit, the spotlight is on flat shapes, also called two-dimensional shapes. Your child counts sides and corners, names a triangle even when it is upside down or stretched thin, draws shapes, and fits small shapes together into bigger ones. After the adding and subtracting unit, this is a hands-on stretch with shapes, and it leads straight into solid shapes and the teen numbers next.
By Robert “Bobby” BarnettMath teacher, parent, and founder of Bobby’s Math Club
What is my child learning in Unit 5?
- Naming triangles, squares, rectangles, and hexagons, shapes with six sides, however they are turned and whatever their size. Learn more: Naming shapes turned any which way
- Counting the sides, the straight edges, and the corners of flat shapes to say how a square and a rectangle are alike and different. Learn more: Comparing shapes by their sides and corners
- Drawing flat shapes and building them with straws or sticks, taking care to make straight sides that meet at the corners. Learn more: Building and drawing shapes
- Putting flat shapes together to make new ones, such as joining two triangles side to side to make a square. Learn more: Putting shapes together to make new shapes
Sample questions to try together
These are real questions from our practice. Tap the speaker to hear one read aloud, or the light bulb for a hint, and talk about the answer together.
Question 1 of 3
What shape do you see?
- Circle
- Square
- Triangle
How you can help
- Draw shapes on paper together, counting each side aloud as you draw it, and ask your child how many corners the finished shape has.
- Fold a square paper napkin corner to corner to make a triangle, then unfold it and talk about how the two triangles made a square.
- Hunt for flat shapes around the kitchen, such as square tiles, round plates, and rectangle cereal boxes, and talk about which have corners and which do not.
Where kids can get stuck
- Calling a square tilted on its corner a diamond, and insisting it is no longer a square.
- Losing track of where they started counting sides, and saying a triangle has 4 sides.
- Joining two triangles corner to corner instead of side to side, leaving a gap instead of a new shape.
Practice makes perfect
Bobby's Math Club has practice problems that adapt to your child’s level, each with a detailed explanation and an easy-to-follow video, so your child can build confidence in these skills one step at a time.
Words your child will hear
- two-dimensional
- Flat, like a shape drawn on paper; also called 2D.
- side
- A straight line that makes part of a flat shape's edge.
- corner
- The point where two sides of a shape meet.
- triangle
- A flat shape with 3 straight sides and 3 corners.
- square
- A flat shape with 4 equal sides and 4 square corners.
- rectangle
- A flat shape with 4 sides and 4 square corners.
- hexagon
- A flat shape with 6 straight sides and 6 corners.
Want to help your child master flat shapes?
In Bobby's Math Club, your child practices these skills 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.
Join the club
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.
Which math standards does Bridges in Mathematics Kindergarten Unit 5 cover?
Bridges in Mathematics Kindergarten Unit 5 covers these math standards. Each one links to what it means, sample questions, and teaching strategies.
For teachers: Unit names and order vary between editions and districts, so your school’s own materials have the exact sequence. Learn how Bobby's Math Club can help your students grow.