Common three-dimensional objects are identified and distinguished by their defining attributes, including flat or curved surfaces, faces, edges, and vertices; examples include cubes, rectangular prisms, pyramids, cones, cylinders, and spheres. The understanding includes recognizing the same solid in different orientations and distinguishing a solid from the two-dimensional shapes that may form its faces. Volume, surface area, nets, and formal classification of solids are beyond this scope.
A 3D object is a solid shape. You can identify it by looking at its surfaces, faces, edges, and vertices:
Remember: a face is a 2D shape on a solid, but the whole object is 3D. For example, a square can be a face of a cube, but the cube is not a square.
Problem: A solid has 6 flat, square faces. It has 12 edges and 8 vertices. What object is it?
Step 1: Look at the faces.
All the faces are flat and square.
Step 2: Count the parts.
The solid has 6 faces, 12 edges, and 8 vertices.
Step 3: Match the attributes.
These attributes match a cube.
Answer: The solid is a cube.
A cube is still a cube if it is turned or tilted. It may look different from another cube, but its defining attributes stay the same.
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