Day 4 — Boolean & if (Decisions)
Yesterday we learned how Python calculates. Today we learn how Python decides.
Calm rule: Python never guesses. It only follows True or False.
🎨 Day 4 Comic — True/False + if
🎨 Day 4 Comic — True/False + if
✅ What is Boolean?
A Boolean is a value that is either True or False. There is nothing in between.
print(True) print(False)
🔍 Comparison Operators (How True/False is created)
Python creates True/False by comparing values.
>greater than<less than>=greater or equal<=less or equal==equal to!=not equal to
print(5 > 3) # True print(5 < 3) # False print(5 == 5) # True print(5 != 5) # False
Important: One equals = means “store”.
Two equals == means “compare”.
📊 Comparison Operators Table
| Operator | Meaning | Example | Result |
|---|---|---|---|
> |
Greater than | 5 > 3 |
True |
< |
Less than | 5 < 3 |
False |
>= |
Greater or equal | 5 >= 5 |
True |
<= |
Less or equal | 4 <= 3 |
False |
== |
Equal to | 5 == 5 |
True |
!= |
Not equal | 5 != 3 |
True |
🧠 Boolean + Variables (A condition is also an expression)
a = 10 print(a > 5) # True print(a == 10) # True
🚦 Introducing if (Decision time)
if means: “Run this code only when the condition is
True.”
age = 18
if age >= 18:
print("Eligible")
Python checks the condition. If it is True, it runs the indented block. If it is False, it skips the block.
🧱 Indentation matters
Python uses spaces to decide what belongs inside
if.
if 5 > 3:
print("Correct indentation") # ✅
if 5 > 3:
print("Wrong indentation") # ❌ IndentationError
Ask the user for age. If age is 18 or more, print
"Eligible".
Optional challenge: Change the age and observe what happens.
✍️ Small practice snippets
1) Compare
print(10 > 50) print(10 == 10) print(10 != 10)
2) Simple if
number = int(input("Enter a number: "))
if number > 50:
print("Big number!")
3) Age check (task)
age = int(input("Enter your age: "))
if age >= 18:
print("Eligible")
Tip: When you see an if, ask: “What condition becomes
True/False?”
🐍 Python Editor (Run)
First run may take a few seconds. Input will appear as browser prompts.
Output will appear here…
Note: If the condition is False, the indented block is skipped, but the program continues.
🔍 Boolean Playground
Enter values for a and b. Python-style
comparisons update instantly.