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Activities

Exploring a regular solid

Background

The face of a solid is called a surface. Surfaces can be flat or curved. A flat surface is called a Plane Surface.

An edge is formed when two surfaces meet. A corner is formed when two or more edges meet.

In geometry an edge is called a line and a corner is called a point.

For the activities in this section you will require a cuboid, cube, cylinder, cone and sphere. If you do not have these regular solid models, you can use solids similar in shape around you or make paper models.

Aim

Recognise regular solids.

Identify the number of surfaces, edges and corners in these solids.

Identify the relationship between surfaces, edges and corners.

Activities

Pick up any of the solids (cuboid, cube, cylinder, cone or sphere)

Count the number of surfaces this solid has. Are all surfaces curved or flat?

Which of your solids have the largest number of surfaces? Do you know of a solid with more surfaces? Do you know of a solid with lesser number of surfaces? What is the least number of surfaces a solid can have? Find such a solid and confirm your answer.

Notice that an edge is formed where two surfaces meet. Observe the solids carefully once again and feel its edges by tracing your finger on them. Is the edge straight or curved? Count the number of edges they have and tabulate your observations.

Does the solid you have chosen have a corner? Feel its corners by pressing your finger on them (corners can be sharp, be careful). Notice that corners are formed where edges meet. How many edges meet at each corner? How many surfaces meet at that corner?

Record your observations. Do you know of a solid, which has more corners? Do you know of a solid, which has lesser number of corners? Can there be a solid without corners?

Related Questions

Try to roll the solid. Which of them can you roll? Why do you think you cannot roll the others?

If you cut a solid with a straight knife, will you get a flat surface or a curved surface?

When you cut a solid once, how many new surfaces are formed?

Can you cut a cuboid in such a way that the pieces remain cuboids?

Which other solids can you cut like this? Which other solids can you not cut like this?

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