Kindergarten · Math · Parent guide
Short answer. K.G.A.3 means your kindergartener tells flat shapes like circles and squares apart from solid shapes like spheres and cubes. Here is how to practice at home.
Quick answer
Your child is learning to sort the shape world into two bins: flat and solid. Flat shapes (the official term is two-dimensional) are things you can draw on paper, like circles, squares, and triangles. Solid shapes (three-dimensional) are things you can hold, like a ball, a dice cube, or an ice cream cone. She should be able to look at a shape and say which kind it is, and use the words flat and solid to explain.
Why parents see this skill
The flat-versus-solid distinction is the frame for all the geometry vocabulary that follows: faces, edges, and vertices only make sense once a child sees that a cube is not just 'a square.' It also sharpens everyday reasoning, because kids start noticing that the circle they draw and the ball they throw are related but different things.
For reference
Identify shapes as two-dimensional (lying in a plane, "flat") or three-dimensional ("solid").Official Common Core source
See it, then try it
You do not need a lesson plan. Look for these signs in ordinary play, reading, and conversation, then choose one short activity.
Set out two boxes labeled with a drawn circle (flat) and a real ball (solid). Gather items and cards: a paper triangle, a soup can, a dice, a square sticky note. Your child sorts everything into the right bin and says the word flat or solid as each item drops.
In a dim room, shine a flashlight on solid objects: a ball, a can, a cone-shaped party hat. The shadow on the wall is flat! Ask her which flat shape the solid object makes. A ball makes a circle, a can held straight makes a rectangle. It is a small wow moment that nails the concept.
Give her 5 minutes to find 3 solid shapes in the kitchen: a sphere (orange), a cylinder (can), a cube-ish box. Then have her find the same shapes drawn flat in a book or draw them herself. Talking through 'the orange is a sphere, my drawing is a circle' is the whole standard in one sentence.
Choose what helps today
Start with the domain guide for context, use the learning library when a concept needs explaining, or print a page when your child is ready to practice.
See every K.G skill in order and how the codes fit together.
Open resourceFilter free pages by the exact math skill your child is practicing.
Open resourceHands-on shape identification, sorting, and geometry practice.
Open resourceParent-friendly ideas for practicing early math in everyday routines.
Open resourcePractice selected for the skill behind K.G.A.3.
Open resourceIs a ball a sphere or a circle?
A ball is a sphere because it is a solid 3D shape. A circle is flat, like a drawing on paper. If your child says “circle” for a ball, gently add, “It looks round like a circle, and the solid shape is called a sphere.”
Do kindergarteners really need to say 2D and 3D?
Yes, but keep it light and practical. Kindergarten children are expected to tell flat shapes from solid shapes, and the words 2D and 3D help them do that clearly. You can pair the words with “flat” and “solid” every time.
My child keeps mixing up square and cube. What helps?
Use touch and contrast. Put a sticky note next to a small box and say, “The sticky note is a flat square, the box is a solid cube or rectangular prism.” Let your child trace the flat face of the box so they can feel how the square is part of the solid shape.
Which 3D shapes matter most in kindergarten?
Focus on cube, cone, cylinder, and sphere. These are the core solid shapes children usually meet in kindergarten. Real objects help most, like a die for cube, a party hat for cone, a can for cylinder, and a ball for sphere.
Which Whizki worksheets help with K.G.A.3?
Look for kindergarten geometry and shape worksheets that ask children to sort flat and solid shapes. The best pages for this skill include circles, squares, triangles, rectangles, hexagons, cubes, cones, cylinders, and spheres. Keep the practice short, then point out the same shapes around the room.
Keep the sequence
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