Sorry this is not polished. This is just published for my Webinar activity.

1. MARY GRACE RASDAS CUETO

2. Forget everything you know
about numbers.
In fact, forget you even know
what a number is.
This is where mathematics
starts.
Instead of math with numbers,
we will now think about math
with things".

3. A set is a well-defined group of objects
(called elements), that share a common
characteristics.
An element is a part
of a set.

4. The name of the set is written in capital
letter.
The elements of the
set is written in small
letters and they are
enclosed in a brace.

5. The symbol ∈ means “element of” and the
symbol ∉ “not element of”
Example:
A = {carabao, cow, horse, goat, sheep}
{carabao} ∈ A
{cow} ∈ A
{lion}∉ A
{snake}∉ A
{horse}∈ A
{sheep}∈ A

6. Let’s practice:
Identify whether the given set is well-defined
set or not well-defined set.
1. Set A = { handsome boys in school}
Answer: Not well-defined set
2. { math teachers in your school}
Answer: Well-defined set
3. { honest politicians }
Answer: Not well-defined set