Recognize 3D Objects
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What you will learn
- 1Name the six common 3D solid shapes
- 2Decide whether a 3D shape has only flat faces or at least one curved surface
- 3Give a real-life example of each 3D shape
Mini Lesson
Unlike 2D shapes, 3D objects have length, width, and height — they take up space. We describe them using faces (flat surfaces), edges (where two faces meet), and vertices (corners). Some 3D shapes also have curved surfaces.
Flat-faced shapes — only flat faces
- Cube — 6 square faces, 12 edges, 8 vertices. All faces are identical. Real life: dice, building block.
- Rectangular prism — 6 rectangular faces, 12 edges, 8 vertices. Real life: cereal box, brick, book.
- Square pyramid — 5 faces (1 square base + 4 triangular sides), 8 edges, 5 vertices. Real life: Egyptian pyramid, tent.
Curved-surface shapes — at least one curved surface
- Sphere — 0 flat faces, 0 edges, 0 vertices. Entirely curved. Real life: ball, orange, globe.
- Cylinder — 2 flat circular faces + 1 curved surface, 2 edges, 0 vertices. Real life: can of soup, paper towel tube.
- Cone — 1 flat circular face + 1 curved surface, 1 edge, 1 vertex (tip). Real life: ice-cream cone, party hat.
Key sorting rule
- Touch every surface: if all surfaces are flat → flat-faced shape.
- If at least one surface curves → curved-surface shape. A curved surface lets a shape roll.
Words to know
3D object
A shape with length, width, and height that takes up space
e.g. A ball is a 3D object.
Face
A flat surface on a 3D object
e.g. A cube has 6 faces.
Edge
Where two faces of a 3D shape meet
e.g. A cube has 12 edges.
Vertex
A corner where edges meet on a 3D shape
e.g. A cube has 8 vertices.
Curved surface
A round, smooth surface, not flat
e.g. A sphere has only a curved surface.
Cylinder
A 3D shape with two flat circle faces and one curved surface
e.g. A soup can is a cylinder.
Ask yourself: "Can I feel any curved surface on this shape? If yes, it belongs in the curved group."
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