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Lessons · Python

Learn Python step by step: 9 lessons with runnable examples

Each lesson pairs a plain-English explanation with code you can run. Every example was executed through the same sandbox the playground uses before it was published, so what you read has been checked, not just typed.

  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 practise 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 practise 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 practise 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 practise 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 practise 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 practise 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 practise 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.