Parent Guide — K.G.A.3
Kindergarten Math · Geometry
What this standard means
Your child learns to tell flat (2D) shapes from solid (3D) shapes.
- Flat: circle, square, triangle drawn on paper or a flat face
- Solid: ball (sphere), box (rectangular prism), can (cylinder)
Why it matters at home
- Pantry sort: cans vs. circles drawn on paper
- Ball vs. paper circle
- Boxes vs. rectangle drawings
- “Can it roll? Can it stack?” for solids
- Shadow play: solid object vs. flat cutout
Connected standards
- Builds on:
- `K.G.A.1` / `K.G.A.2` — naming shapes before classifying flat/solid
- Connects within grade:
- `K.G.B.4` — comparing 2D and 3D shapes’ parts
- `K.G.B.5` — building solids and drawing flat shapes
- Leads to:
- `1.G.A.2` — compose 2D/3D shapes
- `K.MD.A.1` — solids have measurable attributes like weight
- `2.G.A.1` — identify triangles, quadrilaterals, etc., more formally
Try these together (this standard)
1. Is a soccer ball 2D or 3D? 2. Is a triangle on a worksheet 2D or 3D? 3. Find one flat shape and one solid shape in the kitchen.
Problems that show the connections
1. (Uses K.G.A.2) Name the solid (cube/sphere/cylinder) and a flat face you can see. 2. (Uses K.MD.A.1) Describe a solid can by shape class (3D) and an attribute (heavy/light). 3. (Uses K.G.B.5) Build a solid with clay; draw a flat shape on paper.
How you can help
- Use the words flat/solid and 2D/3D together
- Let them hold solids; point to flat drawings
- Faces of solids are flat shapes — a helpful bridge
- Avoid only worksheets; use real objects
- Ask “Can I pick it up and turn it in space?”
- Keep examples obvious at first
Answer key
1. 3D 2. 2D 3. Any correct pair 4. e.g., cube + square face 5. 3D + attribute 6. Built solid + drawn flat shape