The document covers the introduction to sets for grade 7 mathematics, defining key concepts such as well-defined sets, null sets, elements, and cardinality. It includes examples of different types of numbers and sets, illustrating how to identify members of a set using specific symbols. Additionally, it explains the cardinality of sets and how to denote an empty set.

1. Grade 7 – Mathematics
Quarter I
INTRODUCTION TO SETS

2. •define set;
•describe and illustrate well-defined
sets and null sets;
•determine the element/s of a given
set; and
•identify the number of elements or its
cardinality.

3. •Whole numbers {0,1,2,3,4,5,6,…}
•Counting/Natural numbers {1,2,3,4,…}
•Even numbers { 2,4,6,8,10,…}
•Odd numbers { 1,3,5,7,9,…}
•Integers {-∝, 0, +∝ }

4. •Composite numbers {4,6,8,9,10,…}
•Perfect squares {1,4,9,16,25,…}
•Multiples {skip counting by…}
• Factors {numbers which can be divided
without remainder}
•Prime numbers {2,3,5,7,11,…}

5. A B C

6. A B C
A = { }
B = { }
C = { }
A = {shoe, jacket, cap}
B = {ball, doll, toy car}
C={orange, mango, banana}

7. A = {shoe, jacket, cap}
B = {ball, doll, toy car}
C={orange, mango, banana}
A = {set of objects that
can be worn}
B = {set of toys}
C = {set of fruits}

8. •A set is a group or collection of
objects. It is named using CAPITAL
letter. Each object in a set is called a
member or an element of a set.
∈ - the symbol used for element
∉ - the symbol used for not an element

9. Example: A = {school days in a week}
A = {Mon, Tue, Wed, Thurs, Fri}
Mon, Tues, Wed, Thurs, Fri. are called
members or elements of a given set.
Monday ∈ A Sunday ∉ A
Thursday ∈ A Saturday ∉ A

10. 2. B = {counting numbers less than 5}
B = {1, 2, 3, 4}
1, 2, 3, 4 are called members or
elements of a given set.
3. B = {primary colors}
B = {yellow, red, blue}
yellow, red, blue are members or
elements of a given set.

11. Example:
A = {even numbers}
B = {odd numbers}
C = {counting numbers}
Fill in the blank with ∈ or ∉
∉
2 ____ A
8 ____ B
7 ____ C
5 ____ A3 ____ B
-2 ____ C∈ ∈
∈
∉
∉

12. A = {set of primary colors}
B = {set of beautiful girls in school}
C = {set of months in a year}
D = {set of a popular actors}
E = {set of excellent singers}
F = {set of even numbers}
NOT
NOT
NOT

13. A = {set of triangles with 4 sides}
B = {set of months in a year start with B}
C = {set of whole numbers less than 0}
• A set with no members or elements. It is
denoted by the symbol { } for empty set
and ∅ for null set.

14. • Refers to the number of elements in a
given set. It is denoted by the symbol n.
“Cardinality of set A” is written as n(A).
A = {set of primary colors}
A = {yellow, red, blue}
n(A) = 3
B = {school days in a week}
B = {Mon, Tue, Wed, Thurs, Fri}
n(B) = 5

15. • What if there is no elements in a given
set? What will be its cardinality?
A = {set of days in a week start with A}
Number of elements
n(A) = ∅
n(A) = { }
n(A) = 0