A pair of compasses is a tool which can be used to draw circles and arcs. A pair of compasses is sometimes referred to just as a compass.

Checking compass skills

Maths

The constructions covered in this unit are built on in the future unit. In the future unit, pupils construct triangles and construct diagrams following specific restrictions.

The prior unit gave pupils the opportunity to explore polygons and begin to generalise their understanding of interior/exterior angles in regular polygons. In this unit, pupils will use the geometrical properties of a rhombus to perform various constructions. 

In this unit we develop skills in using a pair of compasses and ruler to construct various accurate shapes and angles including triangles, rhombi, perpendicular lines and angle bisectors.

Constructions

The radius is any line segment that joins the centre of a circle to its edge.

Securing the skill of using a pair of compasses

A fixed point is a point that does not change or move.

The circumference of a circle is the perimeter of the circle.

An arc is part of a curve. An arc of a circle is part of the circle’s circumference.

Points A and B are equidistant from a third point C if the distance AC is equal to the distance BC.

Understanding constructing a circle

Scalene triangles have three different-sized angles and three edges of different lengths.

Isosceles triangles have two equal-sized angles. Two of the edges are equal in length.

Equilateral triangles have three equal-sized angles and three edges of equal length. They are regular triangles.

The radius is any line segment that joins the centre of a circle to any point on its circumference.

Constructing triangles

A rhombus is a parallelogram where all sides are the same length.

The plural of rhombus can be referred to as rhombi.

Constructing rhombi

To bisect means to cut or divide an object into two equal parts.

The altitude of a triangle is a line segment from a vertex of a triangle to the opposite edge. It is perpendicular to that edge.

Diagonals of a rhombus

If one shape can fit exactly on top of another using rotation, reflection or translation, then the shapes are congruent.

Constructions

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These lessons will be removed by end of Summer Term 2025.