Videos, worksheets, games and acivities to help Grade 3 students learn to describe 3-D
objects according to the shape of the faces and the number of edges and vertices.

In this lesson, we will learn
3-D objects such as pyramids, prisms, cylinders, cones and spheres and their nets.

A face is a surface on a geometric object. An edge occurs when two faces of a 3-D object meet. A vertex is a point where three or more edges meet. In a pyramid, the vertex is the highest point above a base.

A pyramid has one base. The base is a special face that determines the name of the pyramid. The remaining faces in a pyramid are always triangles that meet at one point or vertex.

A pyramid with a square base is a square pyramid. A square pyramid has 5 faces, 8 edges and 5 vertices.

A pyramid with a triangular base is a triangular pyramid. A triangular pyramid has 4 faces, 6 edges and 4 vertices.

Prism

A prism has 2 bases that are matching polygons. The 2 bases are special faces that determine the name of the prism. The other faces are rectangles.

A prism with 2 rectangular bases is a rectangular prism. A rectangular prism has 6 faces, 12 edges and 8 vertices.
Note that a cube is a special rectangular prism with 6 equal square faces.

A prism with 2 triangular bases is a triangular prism. A triangular prism has 5 faces, 9 edges and 6 vertices.

Cylinder, Cone, Sphere

A cylinder is a 3-D object with 2 flat faces (which are circles), 1 curved face, 2 edges and 0 vertices.
A cone is a 3-D object with 1 flat face (which is a circle), 1 curved face, 1 edge and 1 vertex.
A sphere is a 3-D object with 1 curved face, 0 edges and 0 vertices.

3D-shapes: Faces, vertices and edges

How to find edges and vertices. Cubes, triangular pyramids, square based pyramids, and an explanation of edges, vertices and faces.

Nets of 3-D Objects

A net can be described as a ‘jacket’ for a geometric solid that can be folded to cover or create the surface of the solid. A net is a two-dimensional figure with indicated lines for folding to create a three-dimensional solid.

Geometric nets are matched with their corresponding shapes. Movies of the folding of the geometric nets are included.

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