This document provides an overview of different number systems including natural numbers, whole numbers, integers, and rational numbers. It begins with definitions of each number type and examples of how they are represented on a number line. An activity is described where students classify random numbers into the different categories. Rational numbers between two other rationals are discussed, as well as equivalent rational number representations. The document concludes with sample multiple choice questions to assess understanding.

1. Lecture No. 1
Topic Name: Number System
( A Review)

2. Number System
• Let us start the revision, by looking to the
following video:
https://www.youtube.com/watch?v=8Y82JLMN_Fc
(related to whole numbers, integers and number line)
or
https://www.youtube.com/watch?v=m94WTZP14SA
(maths song on types of numbers)

3. Natural Numbers
Natural numbers start with 1.
There are infinite natural numbers.
There is no largest natural number.
Example: 1,4,6,9,1000 etc.
They can be represented on number line as:

4. Whole Numbers
Whole numbers start from 0.
There are infinite whole numbers.
There is no largest whole number.
Example:0,1,4,6,9,1000 etc.
They can be represented on number line as:

5. Integers
Integers are spread on both sides of the number
line.
Positive integers lie on the right side of 0 and
negative integers on the left side.
There are infinite integers.
There is no largest integer.
Example:0,1,4,6,9,1000, -1, -8 etc.
They can be represented on number line as:

6. Rational Numbers

7. Activity:
To the coordinator:
 Make paper chits containing random numbers.
Divide the blackboard into four parts: Integer,
Natural Number, Rational Number and whole
number.
Call a student randomly and ask him/her to pick a
chit and classify the number in the given category.
( Maximum Time: 10 mins )

8. Rational Number between two
rational numbers
 There exists infinite rational numbers between two
Rational Numbers.
Suppose, we have to find a rational number
between 2 and 4.
 We have (2+4)/2=3, a rational between 2 and 4.
Similarly, between 2 and 3, we have, (2+3)/2=5/2,
i.e, 5/2 is a rational number between 2 and 3.

9. Rational Number between two
rational numbers
 There exists infinite rational numbers between two
Rational Numbers.
Suppose, we have to find a rational number
between 2 and 4.
 We have (2+4)/2=3, a rational between 2 and 4.
Similarly, between 2 and 3, we have, (2+3)/2=5/2,
i.e, 5/2 is a rational number between 2 and 3.

10. Equivalent Rational Numbers
 The representation of rational numbers on the
number line is not unique.
 For example, ¼=2/8=5/20… and so on. These
are called Equivalent Rational Numbers.

11. Now, answer the following
MCQs:
1.0 is a: 3. 22/7 is a :
a.Rational Number a. Rational Number
b.Natural Number b. Integer
c.Whole Number c. Whole Number
d.Both a and c. d. None of the above.
2. Every natural number is a: 4. Every integer is:
a.Whole number a. A whole number
b.Rational number b. A Natural Number
c.Integer c. A Rational Number
d.All the above. d. All the above
Note: Maximum time for each question is 30 secs.

12. Solutions: 1. D
2. D
3. A ( But π is not a rational, the reason
will be discussed in next lecture)
4. C

13. Assessment:

14. Assessment:

15. Note to the coordinator:
• The coordinator should take the print out of the
above sheets.
• Maximum allotted time is 20 minutes.
• After the test, the coordinator should grade the
student on the basis of the performance.
• The solutions can be found at:
http://in.edugain.com/math/grade-8/Rational-Numbers

16. BYE BYE!!
WE WILL COME BACK TOMORROW!!