No, I began to contact compasses in the second volume of the sixth grade of primary school. Compasses don't need to be learned specially, just let students touch them, so as to lay the foundation for learning the circumference and area of a circle later. So we need to know the composition of the circle and how to draw it in the early stage.

Compass is a tool for drawing circles or strings in mathematics and drawing, and is often used for drawing with a ruler. Compasses are made of metal and plastic, including two parts connected by hinges, which can be adjusted.

Structure of compasses:

The compass consists of a pen tip, a rotating shaft, compass legs and a ruler. Wherein, the plunger at the lower end of the pen tip is located at the upper end of the pen body, the lower end of the pen body is screwed at the upper end of the pen tip, the flush end of the small ear is welded at the middle of the outer side of the compass leg, and the lower end of the compass leg is clamped at the upper end of the compass leg.

Characterized in that one side of the pen body is bonded to one side of the hinge, and the other side of the hinge is bonded to the middle of one end of the ruler; Inserts on both sides of the upper end of the seam of the pen body are located at both ends of the rotating shaft, and the shaft body of the rotating shaft is connected to the upper end of the compass leg through a sleeve.

Precautions:

1, the height between the two legs of the compass should be the same.

2. In the process of drawing a circle, the compasses should be slightly inclined by about 30 degrees to make the drawn round lines smooth.

In the process of drawing a circle, the end with the needle (that is, the center of the circle) can't move.

4. In the process of drawing a circle, the distance between two feet (i.e. radius) cannot be changed.

5. Be careful when drawing.