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

Maths

Checking compass skills

Securing the skill of using a pair of compasses

Constructing triangles

Constructing rhombi

Diagonals of a rhombus

Bisecting an angle

Perpendicular bisector of a line segment

Perpendicular to a given line through a given point

Problem solving with constructions

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

A circle is a shape such that every point is {{ }} to its centre.

Sam is stood in the centre of a circle. Which pupil is the closest to Sam?

The pair of compasses in the image are used to draw a circle around the origin of the co-ordinate grid. Which point would lie on the circle?

The pair of compasses in the image are used to draw a circle around the origin of the co-ordinate grid. The diameter of the circle is {{ }} units.

The images show a wrecking ball swinging from a fixed point on a crane. Which image correctly shows the movement of the wrecking ball?

Which part of the circle is highlighted and labelled with a question mark?

Izzy tries to draw a circle with a pair of compasses without moving the ruler. The pencil starts at the 2 cm mark on the ruler. Half way around, the pencil touches the {{ }} cm mark on the ruler.

The image shows a circle with centre at point A. Sofia draws a circle with radius 2 cm with its centre at point B. How many times will the two circles intersect?

The diagram is not to scale. Points A, B, C and D lie on a straight line. The distance from A to D is 20 cm. The radius of the large circle is 8 cm; the radius of the small circle is {{ }}.

Laura draws two circles. One has a radius 5 cm, the other has a radius 9 cm. The distance between the centre points of each circle is 16 cm. Which image matches Aisha's drawings?

Understanding constructing a circle

Lesson outcome