Skip to content

Lessons · Python

Learn Python step by step: 9 lessons with runnable examples

Each lesson pairs a plain-English explanation with code you can run. Try the examples in the playground, compare the output and change an input to see how the behavior changes.

  1. Lesson 1

    Python Printing and Output

    Learn what print really does in Python - quotes and strings, printing values with commas, the sep and end settings, escapes and multi-line text.

    print · output · basics · 1 exercise to practice it

  2. Lesson 2

    Python Variables and Data Types

    Understand what a Python variable really is, how to name one well, and how int, float, str, bool, and None behave when you check and convert types.

    variables · data-types · basics · 1 exercise to practice it

  3. Lesson 3

    Python Arithmetic and Numbers

    How Python does maths - why division always gives a float, what // and % really answer, powers, int versus float, and why 0.1 + 0.2 is not 0.3.

    arithmetic · numbers · operators · floats · 1 exercise to practice it

  4. Lesson 4

    Python Conditionals: if, elif, and else

    Learn how Python decides what to run using if, elif, and else, plus comparison operators, and/or/not, truthiness, and the conditional expression.

    conditionals · control-flow · booleans · 1 exercise to practice it

  5. Lesson 5

    Python For Loops and Iteration

    Learn Python for loops from the ground up - iterate over lists and strings, use range, enumerate and zip, and steer a loop with break and continue.

    loops · iteration · control-flow · 3 exercises to practice it

  6. Lesson 6

    Python Strings

    Learn how Python strings are created, why they are immutable, how indexing and slicing work, and the string methods and f-string formatting you will use most.

    strings · text · f-strings · 2 exercises to practice it

  7. Lesson 7

    Python Lists

    Learn how Python lists store ordered, changeable collections of values, and how to create, access, modify, and iterate over them.

    lists · data-structures · 1 exercise to practice it

  8. Lesson 8

    Python Functions: Defining, Calling, and Returning

    Learn Python functions from scratch - def syntax, parameters versus arguments, return values, keyword and default arguments, *args, **kwargs, and scope.

    functions · parameters · scope

  9. Lesson 9

    Python Dictionaries

    Learn how Python dictionaries map keys to values, read them safely with .get(), add, update and delete entries, loop with .items(), and why lookups are fast.

    dictionaries · data-structures · hash-tables

Reading is half of it

The Python exercises are where you write the code these lessons describe, one idea at a time, with the output checked for you. The playground is for trying any example on this page with your own numbers.