A compass is an instrument used to draw circles or the parts of circles called arcs.  It consists of two movable arms hinged together where one arm has a pointed end and the other arm holds a pencil.

Note that a compass is also called a pair of compasses.

To draw a circle (or arc) with a compass:

• make sure that the hinge at the top of the compass is tightened so that it does not slip
• tighten the hold for the pencil so it also does not slip
• align the pencil lead with the compass's needle
• press down the needle and turn the knob at the top of the compass to draw a circle (or arc)

Example 2

Use a compass to draw a circle of radius 4 cm.