🐍 Python for Teens & Beginners · Lesson 4 of 7

Conditions: if and else

The program decides by itself.

if / else

age = int(input("Age: "))
if age >= 13:
    print("You can make an account")
else:
    print("Ask a parent first")

The colon : and the indentation (4 spaces) matter. Indented lines belong to the if or the else.

Comparisons

==	Equal to (two = signs!)
!=	Not equal to
< >	Less than, greater than
<= >=	Less/greater than or equal

elif: more choices

score = int(input("Score: "))
if score >= 90:
    print("A")
elif score >= 80:
    print("B")
elif score >= 70:
    print("C")
else:
    print("Keep practicing!")

Python checks from the top and runs only the first true branch.

and, or, not

if temp > 60 and not raining:
    print("Go to the park")

Tip

💡 The most common beginner bug: if x = 5 instead of if x == 5. One = stores, two == compares.

✏️ Practice: your turn

Ask for a number and say whether it is even or odd
Write a letter-grade program with if/elif/else
Ask for a password and print “Welcome” only if it matches
Ask for the temperature (°F) and suggest what to wear

✏️ Run Python in your browser, no install ↗

🧠 Quick quiz

Answer all 4 questions correctly to mark this lesson as done.

1. Which compares two values?

2. What marks the lines inside an if?

3. score = 85. Which prints with the code above?

4. What does != mean?

0 of 4 correct

🔀 Conditions: if and else