Lesson 1 of 10

Module 1 · Python for Beginners

First Steps in Python

What programming is, how to run Python in your browser with Google Colab, print, comments, how Python reads your code, and how to read an error message.

About 25 minutes

Open in ColabEvery example as a notebook you can run, edit and save to your Google Drive.

Why Python

A program is a list of instructions for a computer, written in a language it understands. Python is one of the most popular programming languages in the world, and one of the easiest to read: its instructions look close to plain English. It's used for:

data analysis: cleaning, summarising and charting data (pandas, matplotlib);
automation: renaming files, sending reports, filling spreadsheets;
websites and apps: Instagram's servers run Python;
AI and machine learning: most AI tools are built with it.

If you want a career in data or tech, it's a strong first language, and everything you learn here carries over to other languages.

Open Google Colab

You don't need to install anything. Google Colab runs Python in your browser, for free, on Google's computers.

Go to colab.research.google.com and sign in with a Google account.
Click New notebook. It opens with one empty code cell.
Click Untitled0.ipynb at the top and rename it, for example "Python practice".

A notebook is made of cells:

Cell	Holds	How to add
Code cell	Python code you can run	+ Code
Text cell	notes and headings	+ Text

To run a code cell, click the ▶ button on its left, or press Shift + Enter (run and move to the next cell). The output appears under the cell. The notebook saves to your Google Drive automatically.

Your first line of code

Type this in a code cell and run it:

Python · try it yourself

Edit the code and press Run (Ctrl + Enter). Examples on this page share their variables, like cells in a notebook.

Output

Hello, I'm learning Python!

print() is a function: a built-in command that does a job. Its job is to show whatever you put inside the brackets. The text is in quotation marks so Python knows it's text, not code.

You can print several things at once, separated by commas. print puts a space between them:

Python · try it yourself

Edit the code and press Run (Ctrl + Enter). Examples on this page share their variables, like cells in a notebook.

Output

Lagos Abuja Kano
Total: 2500

Python can also calculate. Without quotes, 2 + 3 is a sum:

Python · try it yourself

Edit the code and press Run (Ctrl + Enter). Examples on this page share their variables, like cells in a notebook.

Output

5
2 + 3

The first line works out the answer; the second prints the text exactly as written. Quotes make the difference.

How Python reads your code

Python runs your code one line at a time, from top to bottom:

A four-line program run from the top: a comment is ignored, name stores text, two prints produce output; and a program that stops at an undefined variable with a NameError, so the next line never runs — Python runs code from the top, one line at a time, and stops at an error.TapClick the image to see it full size.

Python · try it yourself

Edit the code and press Run (Ctrl + Enter). Examples on this page share their variables, like cells in a notebook.

Output

First
Second
Third

Each instruction usually goes on its own line. Capitals matter: print works, Print and PRINT don't. And in Python, the spaces at the start of a line mean something (you'll see why in the lesson on conditions), so for now, start every line at the left edge.

Comments

Anything after a # on a line is a comment. Python ignores it; it's a note for people reading your code, including you next month:

Python · try it yourself

Edit the code and press Run (Ctrl + Enter). Examples on this page share their variables, like cells in a notebook.

Output

Comments explain why the code does something. You'll also use # to switch a line off while you test, without deleting it.

When it goes wrong

Errors are normal, even for experts. Python's error messages tell you what went wrong if you read the last line first. The three you'll meet most:

print("Hello)

Output

SyntaxError: unterminated string literal (detected at line 1)

A SyntaxError means Python can't understand the line: here, the closing quotation mark is missing. Look at the line it names, and the one just before it.

print(nmae)

Output

NameError: name 'nmae' is not defined

A NameError means you used a name Python doesn't know: usually a typo, or a variable whose cell you haven't run yet. (After Colab disconnects or restarts, run your earlier cells again.)

Print("Hello")

Output

NameError: name 'Print' is not defined

Capitals matter: Python knows print, not Print.

Summary

You want to...	Write
show text	`print("Hello")`
show several values	`print("Total:", 2500)`
calculate	`print(2 + 3)`
add a note	`# comment`
run a cell in Colab	Shift + Enter
start again after a disconnect	Runtime → Run all

Try it

Open your Colab notebook and work through these. Run your code, then type the result here.

Practice

One bus trip costs ₦700. You make 2 trips a day for 22 days in a month. Write the calculation in Python: how much do you spend on transport in the month?

Practice

What does Python give for "5" + "5"? Type exactly what it shows, quotation marks included.

Practice

What type is 4.21? Type the short name Python uses. (Run type(4.21) to find out; the next lesson explains types.)

Task

6 min

Write a short program with at least three print lines: your name, your course, and a calculation (for example your monthly transport cost), with a comment above it explaining what it works out. Run it in Colab, then paste your code here.

Your work is checked for

At least three print lines
Text in quotes
A calculation with an operator
A comment starting with #

Earn your badge

Take the module check

Questions on this module. Pass and you earn the Python First Steps badge, free.

Create a free account to earn the badge

Lesson 1 of 10

Module 1 · Python for Beginners

First Steps in Python

What programming is, how to run Python in your browser with Google Colab, print, comments, how Python reads your code, and how to read an error message.

About 25 minutes

Open in ColabEvery example as a notebook you can run, edit and save to your Google Drive.

Why Python

data analysis: cleaning, summarising and charting data (pandas, matplotlib);
automation: renaming files, sending reports, filling spreadsheets;
websites and apps: Instagram's servers run Python;
AI and machine learning: most AI tools are built with it.

If you want a career in data or tech, it's a strong first language, and everything you learn here carries over to other languages.

Open Google Colab

You don't need to install anything. Google Colab runs Python in your browser, for free, on Google's computers.

Go to colab.research.google.com and sign in with a Google account.
Click New notebook. It opens with one empty code cell.
Click Untitled0.ipynb at the top and rename it, for example "Python practice".

A notebook is made of cells:

Cell	Holds	How to add
Code cell	Python code you can run	+ Code
Text cell	notes and headings	+ Text

Your first line of code

Type this in a code cell and run it:

Python · try it yourself

Edit the code and press Run (Ctrl + Enter). Examples on this page share their variables, like cells in a notebook.

Output

Hello, I'm learning Python!

print() is a function: a built-in command that does a job. Its job is to show whatever you put inside the brackets. The text is in quotation marks so Python knows it's text, not code.

You can print several things at once, separated by commas. print puts a space between them:

Python · try it yourself

Edit the code and press Run (Ctrl + Enter). Examples on this page share their variables, like cells in a notebook.

Output

Lagos Abuja Kano
Total: 2500

Python can also calculate. Without quotes, 2 + 3 is a sum:

Python · try it yourself

Edit the code and press Run (Ctrl + Enter). Examples on this page share their variables, like cells in a notebook.

Output

5
2 + 3

The first line works out the answer; the second prints the text exactly as written. Quotes make the difference.

How Python reads your code

Python runs your code one line at a time, from top to bottom:

Python · try it yourself

Edit the code and press Run (Ctrl + Enter). Examples on this page share their variables, like cells in a notebook.

Output

First
Second
Third

Comments

Anything after a # on a line is a comment. Python ignores it; it's a note for people reading your code, including you next month:

Python · try it yourself

Edit the code and press Run (Ctrl + Enter). Examples on this page share their variables, like cells in a notebook.

Output

Comments explain why the code does something. You'll also use # to switch a line off while you test, without deleting it.

When it goes wrong

Errors are normal, even for experts. Python's error messages tell you what went wrong if you read the last line first. The three you'll meet most:

print("Hello)

Output

SyntaxError: unterminated string literal (detected at line 1)

A SyntaxError means Python can't understand the line: here, the closing quotation mark is missing. Look at the line it names, and the one just before it.

print(nmae)

Output

NameError: name 'nmae' is not defined

A NameError means you used a name Python doesn't know: usually a typo, or a variable whose cell you haven't run yet. (After Colab disconnects or restarts, run your earlier cells again.)

Print("Hello")

Output

NameError: name 'Print' is not defined

Capitals matter: Python knows print, not Print.

Summary

You want to...	Write
show text	`print("Hello")`
show several values	`print("Total:", 2500)`
calculate	`print(2 + 3)`
add a note	`# comment`
run a cell in Colab	Shift + Enter
start again after a disconnect	Runtime → Run all

Try it

Open your Colab notebook and work through these. Run your code, then type the result here.

Practice

One bus trip costs ₦700. You make 2 trips a day for 22 days in a month. Write the calculation in Python: how much do you spend on transport in the month?

Practice

What does Python give for "5" + "5"? Type exactly what it shows, quotation marks included.

Practice

What type is 4.21? Type the short name Python uses. (Run type(4.21) to find out; the next lesson explains types.)

Task

6 min

Your work is checked for

At least three print lines
Text in quotes
A calculation with an operator
A comment starting with #

Earn your badge

Take the module check

Questions on this module. Pass and you earn the Python First Steps badge, free.

Create a free account to earn the badge