Learning constructions helps develop precision, analytical thinking, and spatial understanding. It is essential for higher-level geometry and practical applications like design and architecture.
The mandatory tools are a ruler, compass, protractor, and set squares. These tools enable accurate constructions of lines, angles, and shapes.
A line segment has two endpoints and a fixed length, whereas a line extends infinitely in both directions and has no endpoints.
Measure both halves of the bisected line segment using a ruler. If the lengths are equal, the bisection is accurate.
Real-life examples include street intersections, the edges of books, and the corners of rooms.
CBSE Notes Class 6 Maths Chapter 8 Playing with Constructions
Chapter 8 of the CBSE Class 6 Maths, Playing with Constructions, introduces students to basic geometric constructions. It builds a strong foundation for understanding shapes, measurements, and the tools needed for precise constructions. Download the Playing with Constructions Class 6 Maths revision notes PDF to revise key concepts and understand the construction steps easily.
Chapter 8 Playing with Constructions CBSE Notes
1.0Playing with Constructions Class 6 Maths Chapter 8 - Revision Notes
Introduction to Construction Tools
Ruler: Used to measure and draw straight lines.
Compass: Helps in drawing circles and arcs of specific radii.
Divider: Used for comparing lengths.
Set Squares: Tools for drawing perpendicular and parallel lines.
Protractor: Measures angles in degrees.
Drawing a Line Segment
Definition: A line segment is a part of a line with two endpoints.
Steps:
Place the ruler on the paper.
Mark two points, say A and B, at the required distance.
Draw a straight line between A and B.
Constructing a Circle
Key Elements of a Circle:
Radius: Distance from the centre to any point on the circle.
Diameter: Twice the radius.
Center: The fixed point inside the circle.
Steps:
Place the compass point on the centre.
Adjust the compass to the required radius.
Rotate the compass to draw the circle.
Perpendicular Lines
Definition: Two lines are perpendicular if they meet at a right angle (90°).
Construction Steps:
Draw a line segment AB.
Place the protractor on the given line segment with its centre at the point where the perpendicular is to be drawn.
Mark the 90° angle using the protractor.
Remove the protractor and use a scale to draw a straight line passing through the marked point. This line will be perpendicular to the original segment.
Squares and Rectangles
Properties of Squares:
All four sides are equal.
Opposite sides are parallel.
Diagonals bisect each other at right angles and are equal in length.
Properties of Rectangles:
Opposite sides are equal and parallel.
All angles are right angles (90°).
Diagonals are equal in length and bisect each other.
Constructing Squares and Rectangles
Steps to Construct a Square:
Draw a line segment of the desired side length.
Use a compass to construct perpendiculars at each endpoint.
Mark the same side length on these perpendiculars and connect the points to form the square.
Steps to Construct a Rectangle:
Draw one side of the rectangle.
Construct perpendiculars at the endpoints using a protractor or set square.
Mark the required length for the opposite side and join the points to form the rectangle.
Points Equidistant from Two Given Points
The concept of a perpendicular bisector is introduced as the set of points equidistant from two fixed points.
Steps to Construct a Perpendicular Bisector:
Draw a line segment AB.
Place the compass point on A and draw an arc above and below AB.
Repeat with the compass point on B.
Connect the intersection points of the arcs to bisect the line segment.
Practical Applications of Constructions
Creating floor plans.
Designing patterns in art and crafts.
Understanding real-life objects like bridges and wheels.
2.0Important Tips for Students
Practice using geometric tools to become familiar with their handling.
Follow the steps of construction accurately to avoid errors.
Verify your construction by measuring with a ruler or protractor.
3.0Practice Questions
Draw a line segment of 7 cm and bisect it.
Construct a circle with a radius of 4.5 cm.
Using a protractor, draw an angle of 120°.
Draw perpendicular lines to a given line segment.
Identify and name the types of angles in the given figure.
Using a ruler and compass: A ruler helps draw straight lines, while a compass is used to draw circles and arcs. Both tools help us make accurate geometric figures.
Circles and their centre: A circle is made up of points that are all at the same distance from a fixed point. This fixed point is called the centre.
Radius of a circle: The radius is the distance from the centre to any point on the circle. For example, if a circle has a radius of 4 cm, every point on its boundary is 4 cm from the centre.
Drawing circles and arcs: A compass can draw a complete circle or just a part of one, called an arc. Keeping the compass opening unchanged helps us draw arcs of the same radius.
Properties of a rectangle: A rectangle has four right angles, each measuring 90°. Its opposite sides are equal.
Properties of a square: A square has four equal sides and four right angles. It also has all the properties of a rectangle.
Naming squares and rectangles: We name a square or rectangle by following its corners in order. For example, rectangle ABCD can also be called BCDA, CDAB or DABC.
Rotated squares and rectangles: A square or rectangle remains the same shape even when it is tilted or turned. Its side lengths and angles do not change.
Constructing squares: Start by drawing one side of the required length. Draw perpendicular lines at its endpoints, mark equal lengths on them, and join the remaining endpoints.
Constructing rectangles: Draw the given side and construct perpendicular lines at its endpoints. Mark the required lengths and join the points to complete the rectangle.
Points on the sides of a rectangle: Moving points along the sides of a rectangle changes their positions and may change the distance between them. Drawing and measuring the joining line segment helps us explore this relationship.
Dividing rectangles into squares: Some rectangles can be divided into two or more equal squares. A rough sketch can help you work out the dimensions before making the final construction.
Diagonals of squares and rectangles: A diagonal joins two opposite corners of a shape. Drawing the diagonals helps us compare their lengths and see how they cross each other.
Constructing a rectangle using a diagonal: If one side and the diagonal are given, a ruler, compass and perpendicular lines can help locate the missing corner.
Finding points at equal distances: A point that is equally distant from two given points can be found using arcs drawn with a compass. The intersection of arcs with equal radii gives a point at the required distance from both centres.
Planning a construction: Before starting, make a rough sketch and note the given measurements. This makes it easier to decide which lines, arcs and perpendiculars to draw first.
4.0Important Formulas – Playing with Constructions
This chapter is mainly about drawing geometric figures rather than learning numerical formulas. The following properties and rules will help you complete the constructions correctly.
Concept
Property or rule
Example
Circle
Every point on a circle is equally distant from its centre.
A circle with a radius of 4 cm has every boundary point 4 cm from the centre.
Rectangle
Opposite sides are equal, and all angles are 90°.
AB = CD and BC = AD
Square
All four sides are equal, and all angles are 90°.
AB = BC = CD = DA
Perpendicular lines
Two perpendicular lines meet at an angle of 90°.
∠ABC = 90°
Equal lengths
A compass can transfer a given length to another line.
A length of 5 cm can be marked on another line using a compass.
Points at equal distances
A point on the intersection of two circles with equal radii is equally distant from their centres.
If PA = QA = 5 cm, then A is equally distant from P and Q.
Constructing a Square with a Given Side
Let us construct a square PQRS with each side measuring 6 cm.
Draw a line segment PQ = 6 cm.
Draw a perpendicular to PQ at P.
Mark S on the perpendicular so that PS = 6 cm.
Draw a perpendicular to PQ at Q.
Mark R on this perpendicular so that QR = 6 cm, on the same side of PQ as S.
Join R and S to complete the square PQRS.
Check that all four sides are equal and each angle measures 90°.
Constructing a Rectangle with Given Side Lengths
Let us draw a rectangle ABCD with sides of 6 cm and 4 cm.
Draw AB = 6 cm.
Draw perpendicular lines to AB at A and B.
Mark AD = 4 cm and BC = 4 cm on the same side of AB.
Join C and D to complete the rectangle ABCD.
Check that AB = CD, AD = BC, and all four angles are 90°.
Constructing a Rectangle Using One Side and a Diagonal
Suppose a rectangle has one side of 5 cm and a diagonal of 7 cm.
Draw DC = 5 cm.
Draw a perpendicular to DC at C.
Open the compass to 7 cm and, with D as the centre, draw an arc that cuts the perpendicular at B.
Draw a perpendicular to DC at D.
Draw a perpendicular to BC at B. Let the perpendiculars from D and B meet at A.
Join AB and AD to complete rectangle ABCD.
Check that the angles are right angles, the opposite sides are equal, and DB = 7 cm.
Finding Points Equidistant from Two Given Points
Suppose you need to find a point A that is 5 cm from both B and C.
Draw an arc with B as the centre and a radius of 5 cm.
Draw another arc with C as the centre and the same radius.
Mark an intersection of the arcs as A.
Join A to B and A to C.
Since both arcs have a radius of 5 cm, AB = AC = 5 cm. Therefore, A is equally distant from B and C.
5.0Learning Guide for Class 6 Maths Playing with Constructions – Chapter 8
Practising with a compass: Mark a point P on paper and set your compass to 4 cm using a ruler. Keep the pointed end at P and turn the compass to draw a circle. Every point on the circle will be 4 cm from P.
Drawing circles and arcs: Draw circles with different radii. Then try drawing only a part of a circle to practise making arcs.
Making simple drawings with a compass: Try drawing simple patterns, wavy lines or pairs of circles using a ruler and compass. Changing the compass opening and the position of its point will help you create different shapes.
Identifying squares and rectangles: Draw both shapes and measure their sides and angles. Check that opposite sides of a rectangle are equal and that all four sides of a square are equal.
Recognising rotated shapes: Turn your paper after drawing a square or rectangle. Notice that the shape remains the same even when it is tilted.
Constructing a square: Draw a square with a side of 6 cm using a ruler and compass. Measure its sides and angles to check whether your construction is correct.
Drawing rectangles of different sizes: Construct rectangles measuring 4 cm by 6 cm and 2 cm by 10 cm. Compare their dimensions and check whether both follow the properties of a rectangle.
Exploring points on rectangle sides: Draw rectangle ABCD and mark points X and Y on opposite sides. Move the points to different positions and measure XY. Observe how the distance changes.
Dividing a rectangle into squares: Draw a rectangle that can be divided into two equal squares. Then try dividing another rectangle into three equal squares. Plan the dimensions before drawing the final figures.
Drawing a square inside a rectangle: Draw a rectangle measuring 8 cm by 4 cm. Try placing a square inside it so that both shapes have the same centre. Use a rough sketch to plan where the corners should lie.
Exploring diagonals: Draw rectangle PQRS and join P to R and Q to S. Measure both diagonals and compare their lengths. Repeat the activity with a square and note what you observe.
Constructing a rectangle using a diagonal: Draw a rectangle with one side measuring 5 cm and a diagonal measuring 7 cm. Use a compass and perpendicular lines to locate the missing corner.
Making a geometric house: Try drawing a house-shaped figure using a ruler and compass. Use arcs to locate points at the required distances, then join the points to complete the shape.
Checking your construction: Measure the sides and angles after completing a figure. If something does not match the given measurements, check the compass opening and the positions of the perpendicular lines.
9.0Benefits of CBSE Notes for Class 6 Maths Chapter 8 - Playing with Constructions
Enhanced Accuracy in Constructions: Following well-structured CBSE Notes helps students perform constructions precisely, leading to correct geometric figures.
Time-Saving Resource: The CBSE Notes for Class 6 condense the essential information, saving students the time of sifting through lengthy textbook chapters.
Building a Strong Foundation: Mastering the concepts in this chapter lays a crucial foundation for more advanced geometry topics in higher classes.
Self-Paced Learning: Students can refer to the notes at their own pace, revisiting concepts they find challenging.
Preparation for Assessments: The notes often include important definitions, properties, and example problems that are likely to appear in school assessments.