Python Conditionals for Beginners: if, elif, else 🤔

A program that can’t make decisions is like a robot that can only walk straight. Boring!

A program with conditionals is a smart assistant that analyzes a situation and acts differently depending on it. Cool!

Today we’ll teach your programs to think.

🎯 What Are Conditionals?

A conditional is about making a choice: “if… then…”

Real-world examples:

IF it is raining:
    take an umbrella

IF temperature > 30:
    turn on the air conditioner

IF password is correct:
    grant access

In Python it looks almost the same!

🔥 The if Statement — Basic Check

Syntax:

if condition:
    code that runs when condition is True

Key elements:
1. if — the keyword
2. condition — what we’re checking
3. : — colon is required!
4. 4-space indent — everything inside the if block

Simplest example:

age = 18

if age >= 18:
    print("You are an adult! 🎓")

What happens:
1. Python checks: age >= 18 → 18 >= 18 → True
2. Condition is True → the code inside runs
3. We see: “You are an adult! 🎓”

Change age = 15 and run again — nothing is printed!

Try it yourself:

password = input("Enter password: ")

if password == "secret123":
    print("✅ Access granted!")

Important: == is equality check, while = is assignment!

x = 5      # Assignment: x is now 5
x == 5     # Check: is x equal to 5? → True

✅ if-else: Two Branches

Often you need to handle both cases: when True and when False.

Syntax:

if condition:
    code if True
else:
    code if False

Example:

age = int(input("How old are you? "))

if age >= 18:
    print("🎓 You are an adult")
else:
    print("👶 You are still a child")

What happens:
- If age >= 18 → first block
- Otherwise (age < 18) → second block
- Only ONE of the blocks runs!

Guess the Number game:

secret = 7
guess = int(input("Guess a number from 1 to 10: "))

if guess == secret:
    print("🎉 Correct!")
else:
    print(f"😢 Wrong. It was: {secret}")

🎯 elif: Multiple Choices

What if you have more than two cases?

Syntax:

if condition1:
    code1
elif condition2:
    code2
elif condition3:
    code3
else:
    code4

elif = else if = “otherwise if”

Example — grading system:

score = int(input("Your score (0-100): "))

if score >= 90:
    print("🌟 Grade: A (Excellent!)")
elif score >= 80:
    print("👍 Grade: B (Good)")
elif score >= 70:
    print("📝 Grade: C (Satisfactory)")
elif score >= 60:
    print("📚 Grade: D (Passing)")
else:
    print("❌ Grade: F (Fail)")

How it works:
1. Checks >= 90 — if True, runs and stops, the rest are skipped
2. If False — checks >= 80
3. And so on, top to bottom
4. If all are False — runs else

Order matters!

# ❌ WRONG — first condition catches everything!
if score >= 60:
    print("D")
elif score >= 80:  # Never runs!
    print("B")

# ✅ CORRECT — from largest to smallest
if score >= 80:
    print("B")
elif score >= 60:
    print("D")

🔍 Comparison Operators

What can you check?

Examples:

x = 10

if x > 5:
    print("x is greater than 5")  # Runs

if x != 20:
    print("x is not 20")  # Runs

if x == 10:
    print("x equals 10")  # Runs

if x <= 10:
    print("x is less than or equal to 10")  # Runs

Checking strings:

name = input("Your name: ")

if name == "Anna":
    print("Hello, Anna!")

city = "New York"
if city != "London":
    print("This is not London")

Important: Case matters!

if "anna" == "Anna":  # False!
    print("Equal")

# To ignore case:
name = input("Name: ").lower()  # Convert to lowercase
if name == "anna":
    print("That's Anna!")

💡 Useful Examples

Checking parity:

number = int(input("Enter a number: "))

if number % 2 == 0:
    print(f"{number} is even")
else:
    print(f"{number} is odd")

% is the modulo operator. Even numbers divide by 2 with no remainder!

Checking a range:

age = int(input("Age: "))

if age < 0:
    print("❌ Invalid age")
elif age < 13:
    print("👶 Child")
elif age < 20:
    print("🎓 Teenager")
elif age < 60:
    print("💼 Adult")
else:
    print("👴 Senior")

Traffic light:

color = input("Traffic light color: ").lower()

if color == "green":
    print("🟢 Go!")
elif color == "yellow":
    print("🟡 Get ready!")
elif color == "red":
    print("🔴 Stop!")
else:
    print("🤔 That's not a valid traffic light color")

⚠️ Common Mistakes

1. Forgot the colon:

# ❌ Error!
if age >= 18
    print("OK")

# ✅ Correct:
if age >= 18:
    print("OK")

2. Forgot the indentation:

# ❌ Error!
if age >= 18:
print("OK")

# ✅ Correct (4 spaces or Tab):
if age >= 18:
    print("OK")

3. Used = instead of ==:

# ❌ Assignment instead of comparison!
if age = 18:
    print("OK")

# ✅ Equality check:
if age == 18:
    print("OK")

4. Condition in else:

# ❌ else doesn't take a condition!
if x > 10:
    print("High")
else x < 5:
    print("Low")

# ✅ Use elif:
if x > 10:
    print("High")
elif x < 5:
    print("Low")
else:
    print("Medium")

🎮 Practice Tasks

Easy level:

1. Password check
Ask for a password. If it’s “python123”, print “Access granted”, otherwise “Access denied”.

2. Age check
Ask for an age. Determine the category: child (<13), teenager (13–17), adult (18+).

3. Discount calculator
Ask for a purchase amount. If >= 1000 — 10% discount; if >= 5000 — 20% discount.

Medium level:

4. Time of day
Ask for the hour (0–23). Print: night, morning, afternoon, or evening.

5. Grade converter
Ask for a score (0–100). Print the grade: A (90+), B (80+), C (70+), D (60+), F (<60).

6. Leap year check
Ask for a year. Determine if it’s a leap year (divisible by 4 but not by 100, or divisible by 400).

🚀 Summary

You learned:

✅ Use if for a single condition
✅ Use if-else for two branches
✅ Use if-elif-else for multiple choices
✅ Apply comparison operators
✅ Avoid common mistakes

Next step: Learn logical operators (and, or, not) to combine conditions!

Practice in CodeHS — write several programs with conditionals. Programming is like a sport: the more you practice, the better you get! 💪