Geometrical Instruments

overview

In this page, overview of the geometrical instruments is provided

• graduated ruler or scale

• compass

• protractor

• divider

• set-squares or set-triangles

ruler / scale

The geometrical instrument in the figure is called a "ruler".

A "ruler" is used to construct a straight line.

The marks or graduations on the ruler show the length measure in millimeter and centimeter.

Other than to construct straight lines, A "ruler" is used to measure a line-segment.

The word "ruler" means: a straight stick.

The word "ruler" is derived from a root word meaning straight stick.

The phrase "graduated ruler" means: a straight stick with grade of length measure marked on them.

Note: A ruler is also referred with the name "scale".

summary

**Graduated Ruler or scale** : A ruler is a straight stick with grade of length measure marked. It is used to construct straight lines and measure a line-segment.

compass

The geometrical instrument in the figure is called a "compass".

A "compass" is used to construct an arc of given radius. The arc has points that are in equal distance from the center point.

The word "compass" is (possibly) from root words "com+pace" meaning "together+take-steps".

summary

**Compass** : An instrument to measure a length and construct an arc of a given radius.

divider

The geometrical instrument in the figure is called a "divider".

A "divider" is used to measure the length between two points.

summary

**Divider** : is a geometrical instrument which is used to measure the length between two points.

protractor

The geometrical instrument in the figure is called a "protractor".

A "protractor" is used to mark an angle of given measure.

The word "Protractor" is from root words "protract+tor", which means "draw-out or lengthen a line".

summary

**Protractor** : is a geometrical instrument which is used to mark a measure of an angle.

set sequares

The geometrical instrument in the figure is called a "set squares" or a "set triangles".

The name "set squares" calls by the two $90}^{\circ$ angles provided by the instruments.

The name "set triangles" calls by the shape of the two pieces. Both names are used.

A "set squares" is used

• to construct perpendicular and parallel lines

• to measure standard angles $90}^{\circ$, $30}^{\circ$, $45}^{\circ$, $60}^{\circ$ etc.

summary

**Set Squares or Set Triangles** : is a pair of triangular pieces used to construct parallel lines or to measure the standard angles $90}^{\circ$, $30}^{\circ$, $45}^{\circ$, $60}^{\circ$ etc.

summary

**Graduated Ruler or scale** : A ruler is a straight stick with grade of length measure marked. It is used to construct straight lines and measure a line-segment.

**Compass** : An instrument to measure a length and construct an arc of a given radius.

**Divider** : is a geometrical instrument which is used to measure the length between two points.

**Protractor** : is a geometrical instrument which is used to mark a measure of an angle.

**Set Squares or Set Triangles** : is a pair of triangular pieces used to construct parallel lines or to measure the standard angles $90}^{\circ$, $30}^{\circ$, $45}^{\circ$, $60}^{\circ$ etc.

Outline

The outline of material to learn "Construction / Practical Geometry at 6-8th Grade level" is as follows.
Note: * click here for detailed outline of "constructions / practical geometry".*

• Four Fundamenatl elements

→ __Geometrical Instruments__

→ __Practical Geometry Fundamentals__

• Basic Shapes

→ __Copying Line and Circle__

• Basic Consustruction

→ __Construction of Perpendicular Bisector__

→ __Construction of Standard Angles__

→ __Construction of Triangles__

• Quadrilateral Forms

→ __Understanding Quadrilaterals__

→ __Construction of Quadrilaterals__

→ __Construction of Parallelograms__

→ __Construction of Rhombus__

→ __Construction of Trapezium__

→ __Construction of Kite__

→ __Construction of Rectangle__

→ __Construction of Square__