K.G.3: Flat Shapes and Solid Shapes
Also written as K.G.A.3 and CCSS.MATH.CONTENT.K.G.A.3 · Cluster: Identify and describe shapes.
The Official Wording
Identify shapes as two-dimensional (lying in a plane, "flat") or three-dimensional ("solid").
Common Core State Standards, Kindergarten, Geometry · Read it at the source · Checked October 14, 2026
What K.G.3 Means in Plain English
Kindergartners sort shapes into two kinds: flat ones that lie on the paper, like a square or a circle, and solid ones you can pick up and hold, like a cube or a ball. A flat shape has no thickness, a solid takes up room in your hand.
The trap is that a cube has squares on it and a can has circles on its ends, so children name the solid after its face. Comparing flat and solid shapes by their parts is K.G.4, and 1st grade builds new shapes from cubes, cones and cylinders (1.G.2).
K.G.3 I Can Statements
- I can tell whether a shape is flat or solid.
- I can name flat shapes like circle, square and triangle.
- I can name solid shapes like cube, sphere, cone and cylinder.
K.G.3 Worked Example
A paper square and a wooden cube side by side, with the one test that tells them apart.
On the table are a paper square and a wooden block. Which one is flat and which is solid?
- Try to lay each one flat on the table. The paper square disappears into the tabletop.paper square: lies flat
- The block sticks up. You can see its top and its sides at the same time.wooden block: sticks up
- Pick each one up. The paper is nothing but an outline, and the block fills your hand.paper: thin, block: fills the hand
- Name them. The flat one with four equal sides is a square. The solid one with squares all over it is a cube.square is flat, cube is solid
Check it: Stack them. A cube sits on top of another cube. A paper square cannot hold anything up, because there is nothing there to stand on.
Common Mistakes with K.G.3
Calling a cube a square
Holds up the block and says “square”
Try this: Count the squares on the block together, all six, then ask how a square could have six squares. Six faces means a cube.
A circle and a ball are the same
A drawn circle and a tennis ball both get the name “circle”
Try this: Roll each one. The ball rolls across the floor because it is solid, and the drawn circle can only lie on the page.
A drawing of a cube looks flat
A photo of a cube on the worksheet is sorted with the flat shapes
Try this: Keep real solids on the table beside the worksheet, and let the child match the picture to the object before sorting.
Where K.G.3 Fits
Practice K.G.3
Quick Check
- Is a sheet of paper cut into a triangle flat or solid?
- Name two solid shapes you could find in a kitchen.
- Kai says the dice is a square because it has squares on it. What is the dice really, and why?