Construction – JSS1 Mathematics Lesson Note (Third Term)

To construct a geometrical figure means to draw it accurately. Construction needs a sharp pencil, compasses, a protractor and a good ruler. Set squares, dividers and other instruments may also be needed. The ruler draws straight lines and measures length, the protractor measures and constructs angles, and the pencil draws straight and curved lines.

Behavioural objectives

By the end of the lesson, students should be able to:

1. State what it means to construct a geometrical figure.
2. List the instruments needed for construction.
3. State the use of the ruler, the protractor and the pencil.

What is construction?

To construct a geometrical figure means to draw it accurately. Generally, to carry out construction, you need a sharp pencil, compasses, a protractor and a good ruler. Other mathematical instruments or equipment, such as set squares and dividers, may also be necessary.

What are the uses of the main construction instruments?

The ruler

The ruler is used for drawing straight lines and for measuring lengths in both centimetres and inches.

The protractor

A protractor is used for measuring and constructing angles.

The pencil

A pencil with a sharp point is used for drawing straight and curved lines. Drawing pencils may be soft or hard.

Evaluation

1. What does it mean to construct a geometrical figure?
2. List four instruments used for construction.
3. State two uses of the ruler.
4. Which instrument is used for measuring and constructing angles?

Assignment

1. Name the instruments you need to carry out a construction.
2. State the use of the pencil in construction and say how the point of the pencil should be.