Welcome back to the Python Tutorial Series for Beginners! 🎉

In Lesson 8, we learned about sets – collections of unique items and how to perform set operations.

Now in Lesson 9, we’ll explore conditional statements – the way Python makes decisions.

By the end of this lesson, you’ll understand:

• Why we need conditions in programming
• if, elif, and else statements
• Comparison and logical operators
• Nested conditions
• Real-world use cases
• Beginner exercises

🔹 What are Conditional Statements?

In real life, we often make decisions:

👉 “If it’s raining, I’ll take an umbrella. Otherwise, I won’t.”

In Python, we use conditional statements to let our programs decide what to do depending on certain conditions.

🔹 1. The if Statement

age = 18

if age >= 18:
   print("You are eligible to vote")

👉 If the condition is True, the block of code runs.

🔹 2. The if...else Statement

age = 16

if age >= 18:
   print("You are eligible to vote")
else:
   print("You are not eligible to vote")

🔹 3. The if...elif...else Statement

👉 Use when you have multiple conditions:

marks = 75

if marks >= 80:
   print("Grade: A")
elif marks >= 60:
   print("Grade: B")
elif marks >= 40:
   print("Grade: C")
else:
   print("Grade: F")

🔹 4. Comparison Operators

Conditions often use comparison operators:

🔹 5. Logical Operators

Combine multiple conditions using logical operators:

age = 20
country = "Nigeria"

if age >= 18 and country == "Nigeria":
   print("You can vote in Nigeria")
   
if age < 18 or country != "Nigeria":
   print("You cannot vote here")
   
if not age < 18:
   print("You are an adult")

🔹 6. Nested Conditions

You can place one if inside another:

age = 25
citizen = True

if age >= 18:
   if citizen:
       print("You are eligible to vote")
   else:
       print("You must be a citizen to vote")
else:
   print("You are not eligible")

🔹 7. Real-World Use Cases

✅ Login system check

username = "admin"
password = "1234"

if username == "admin" and password == "1234":
   print("Login successful")
else:
   print("Invalid credentials")

✅ Discount eligibility

amount = 120

if amount >= 100:
   print("You get a discount!")
else:
   print("No discount available")

🔹 Exercises for Beginners

Try these in a new file (lesson9.py):

1. Write a program that checks if a number is positive, negative, or zero.
2. Write a program that asks for your age and prints whether you are a child, teenager, adult, or senior.
3. Write a program to check if a student passed or failed (pass mark = 50).
4. Write a program to check if a given year is a leap year.
5. Challenge: Write a login system where the correct username is "user" and password is "pass123".

🎯 Recap

In this lesson, you learned:
✅ Conditional statements help programs make decisions
✅ if, elif, and else control the flow of logic
✅ Comparison and logical operators make conditions powerful
✅ Nested conditions let you check multiple layers of logic
✅ Real-world examples include logins, discounts, and validations

Next up: Lesson 10 – Loops in Python 🔄 (where we repeat tasks efficiently).