Is the Variables & Types lesson free?

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

How long does the Variables & Types lesson take?

About 5 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 Variables & Types 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 Variables & Types lesson?

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

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Beginner·5 min·basics · types

Variables & Types

You’ll be able to

Assign values to variables using Python's dynamic typing
Recognize the four core types: int, float, str, bool
Convert between types safely with int(), str(), float()
Use type() to inspect what type a variable holds

Why this matters

Type confusion is the #1 bug in beginner code and a favorite interview trap. Real jobs using pandas or FastAPI expect type coercion instincts, because a CSV column read as str will silently break every sum() and comparison downstream.

Common pitfalls

Using input() and comparing to a number: input() returns str, so x == 5 is always False. Wrap with int().
Reassigning built-in names like list = [1,2,3] shadows the type and breaks later list(...) calls.
Assuming int('3.5') works. It raises ValueError; use float('3.5') first, then int().

Python figures out the type for you, but you should still know what you're holding.

The basics

int — whole numbers (27)
float — decimals (1.78)
str — text ("Ada")
bool — True or False

type(x).__name__ tells you what type a value is.

Try it

Add a city variable and print it.
What happens if you add age + height? Does the type change?

Practice

3 graded exercises

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

Progress0 / 3

Exercise 1
Create an integer variable age equal to 30, then print it.
Exercise 2
Create name = "Ada" and age = 30, then use one f-string to print exactly Ada is 30 years old.
Exercise 3
The variable raw_price holds the string "499". Convert it to an integer, add 100 (a shipping fee), and print the total.

← PreviousHello, World!Next →Numbers & Math

Variables & Types

You’ll be able to

Assign values to variables using Python's dynamic typing
Recognize the four core types: int, float, str, bool
Convert between types safely with int(), str(), float()
Use type() to inspect what type a variable holds

Why this matters

Common pitfalls

Using input() and comparing to a number: input() returns str, so x == 5 is always False. Wrap with int().
Reassigning built-in names like list = [1,2,3] shadows the type and breaks later list(...) calls.
Assuming int('3.5') works. It raises ValueError; use float('3.5') first, then int().

Python figures out the type for you, but you should still know what you're holding.

The basics

int — whole numbers (27)
float — decimals (1.78)
str — text ("Ada")
bool — True or False

type(x).__name__ tells you what type a value is.

Try it

Add a city variable and print it.
What happens if you add age + height? Does the type change?

Practice

3 graded exercises

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

Progress0 / 3

Exercise 1
Create an integer variable age equal to 30, then print it.
Exercise 2
Create name = "Ada" and age = 30, then use one f-string to print exactly Ada is 30 years old.
Exercise 3
The variable raw_price holds the string "499". Convert it to an integer, add 100 (a shipping fee), and print the total.