Is the If / Else & Loops lesson free?

Yes. The first 5 lessons on PyRun are free forever — no signup, no card. If / Else & Loops runs real Python in your browser via Pyodide.

How long does the If / Else & Loops lesson take?

About 7 minutes end-to-end. It's a hands-on lesson — you read a paragraph, edit the code, and run it in the same tab.

Do I need to install Python to try the If / Else & Loops lesson?

No install required. PyRun runs real CPython in your browser via Pyodide (Python compiled to WebAssembly). Works on Chrome, Firefox, Safari, and Edge — desktop or mobile.

What level is the If / Else & Loops lesson?

Beginner level. No prior Python required — good starting point.

← All lessons

Beginner·7 min·basics · control flow

If / Else & Loops

You’ll be able to

Write if, elif, and else branches to make decisions
Iterate over ranges with for and range()
Combine conditions using and, or, not
Understand Python's indentation rules for code blocks

Why this matters

Clean branching separates readable code from spaghetti. Interviewers watch how candidates structure if/elif chains, and code review at any real company will call out nested conditionals deeper than two levels.

Common pitfalls

Writing if x == True: instead of if x:. The explicit compare fails for truthy non-bool values like 1 or 'yes'.
Using = instead of == inside conditions. Python raises SyntaxError, but the muscle memory from other languages persists.
Chaining comparisons wrong: if 0 < x < 10 is valid Python, but if x > 0 and < 10 is a syntax error.

Indentation matters in Python. Code inside an if or a for is indented (4 spaces).

Pieces

if / elif / else — choose a path
for x in range(a, b) — iterate a up to but not including b
% — the modulo operator (remainder of division)

Try it

Extend FizzBuzz to 30.
Add a "Bazz" for multiples of 7.

Practice

3 graded exercises

Write the code, click Check. We’ll tell you exactly what to fix.

Progress0 / 3

Exercise 1
The variable n is set. Print "even" if it's even, otherwise "odd". Test with n = 7.
Exercise 2
Print FizzBuzz for numbers 1 through 10 — Fizz on multiples of 3, Buzz on multiples of 5, FizzBuzz on multiples of both, otherwise the number.
Exercise 3
Given score = 82, print the grade: "A" if ≥90, "B" if ≥75, otherwise "C".

← PreviousStrings Next →While Loops & break/continue

If / Else & Loops

You’ll be able to

Write if, elif, and else branches to make decisions
Iterate over ranges with for and range()
Combine conditions using and, or, not
Understand Python's indentation rules for code blocks

Why this matters

Common pitfalls

Writing if x == True: instead of if x:. The explicit compare fails for truthy non-bool values like 1 or 'yes'.
Using = instead of == inside conditions. Python raises SyntaxError, but the muscle memory from other languages persists.
Chaining comparisons wrong: if 0 < x < 10 is valid Python, but if x > 0 and < 10 is a syntax error.

Indentation matters in Python. Code inside an if or a for is indented (4 spaces).

Pieces

if / elif / else — choose a path
for x in range(a, b) — iterate a up to but not including b
% — the modulo operator (remainder of division)

Try it

Extend FizzBuzz to 30.
Add a "Bazz" for multiples of 7.

Practice

3 graded exercises

Write the code, click Check. We’ll tell you exactly what to fix.

Progress0 / 3

Exercise 1
The variable n is set. Print "even" if it's even, otherwise "odd". Test with n = 7.
Exercise 2
Print FizzBuzz for numbers 1 through 10 — Fizz on multiples of 3, Buzz on multiples of 5, FizzBuzz on multiples of both, otherwise the number.
Exercise 3
Given score = 82, print the grade: "A" if ≥90, "B" if ≥75, otherwise "C".