Lesson 2: Installing Python & IDE Setup

Course: Python Fundamentals | Duration: 2 hours | Level: Absolute Beginner

Learning Objectives

By the end of this lesson, students will be able to:

• Download and install Python 3 on Windows, Mac, or Linux
• Verify that Python installed correctly using the command line
• Install and configure VS Code as their code editor
• Create a new Python file and run it from VS Code
• Use the Python interactive shell (REPL) for quick experiments

Prerequisites

• Lesson 1: What is Programming?
• A laptop with internet connection
• Administrator/admin password for your computer (to install software)

Lesson Outline

Part 1: Installing Python (30 minutes)

Explanation

Before we can write Python programs, we need to install two things:

1. Python itself - the interpreter that runs our code
2. A code editor - a program we use to write code comfortably

Think of it this way: Python is the engine, and the code editor is the steering wheel and dashboard. You could technically write Python in Notepad, but a proper editor gives you helpful features like syntax highlighting (colors that help you read code), error detection, and much more.

Teacher's Note: This lesson can get messy in a large class because every student has a different computer setup. Plan for this. Have teaching assistants walk the aisles, and use the troubleshooting guide at the end of this lesson. Common issues are documented there.

What version of Python? Always install Python 3 (specifically Python 3.10 or newer). Python 2 is old and no longer supported. If you see "Python 3.11" or "Python 3.12", that's great - install it!

Step-by-Step Installation

Windows:

1. Open your web browser and go to python.org
2. Click the yellow "Download Python 3.X.X" button (the big one)
3. Run the downloaded .exe file
4. IMPORTANT: Check the box that says "Add Python to PATH" (this is crucial!)
5. Click "Install Now"
6. Wait for installation to complete
7. Click "Close"

Mac:

1. Open your web browser and go to python.org
2. Click "Downloads" then "macOS"
3. Download the latest Python 3 installer (.pkg file)
4. Double-click the downloaded file
5. Follow the installation wizard
6. When asked about SSL certificates, run the "Install Certificates" command

Linux (Ubuntu/Debian):

sudo apt update
sudo apt install python3 python3-pip

Examples

Verifying the installation works:

After installing, open your Terminal (Mac/Linux) or Command Prompt (Windows):

# Type this and press Enter:
python --version
 
# You should see something like:
# Python 3.11.4
 
# If that doesn't work, try:
python3 --version

Common Question: "I typed python --version and it says 'Python 2.7'. What do I do?" Use python3 instead of python. Some computers have both Python 2 and Python 3 installed. We always want Python 3.

# To check which Python you're using:
python3 --version
# Should show Python 3.x.x
 
# Where is Python installed?
which python3    # Mac/Linux
where python     # Windows

Practice

Verify your installation:

1. Open Terminal (Mac/Linux) or Command Prompt (Windows)
2. Type python3 --version and press Enter
3. Write down the version number you see
4. Raise your hand if you see an error - we'll help you fix it

Part 2: Installing VS Code (30 minutes)

Explanation

VS Code (Visual Studio Code) is a free code editor made by Microsoft. It's used by millions of professional developers worldwide and it's perfect for beginners too.

Why VS Code over other editors?

• Free and open source
• Works on Windows, Mac, and Linux
• Excellent Python support
• Great extensions (add-ons)
• Used by professionals (relevant for future employment)
• The most popular developer tool in the world

Alternative editors (if VS Code doesn't work on your computer):

• IDLE (comes with Python - basic but works)
• Thonny (specifically designed for beginners - great fallback)
• PyCharm Community Edition (powerful but heavy)

Step-by-Step VS Code Setup

Installation:

1. Go to code.visualstudio.com
2. Click the big "Download" button (it auto-detects your OS)
3. Run the installer and follow the prompts
4. Launch VS Code

Installing the Python extension:

1. Open VS Code
2. Click the Extensions icon on the left sidebar (looks like 4 squares)
3. In the search bar, type "Python"
4. Click "Install" on the extension by Microsoft (it's the top result)
5. Wait for it to install

Selecting your Python interpreter:

1. Press Ctrl+Shift+P (Windows/Linux) or Cmd+Shift+P (Mac)
2. Type "Python: Select Interpreter"
3. Choose the Python 3.x version you installed

Examples

Creating and running your first file:

1. In VS Code, click File → New File
2. Save it as "hello.py" (File → Save As)
3. Type this code:
   print("Hello from VS Code!")
4. Right-click anywhere in the file
5. Click "Run Python File in Terminal"

Expected result in the terminal at the bottom:

Hello from VS Code!

If you see that - congratulations! Your setup is working!

Teacher's Note: Walk around the room at this point. At least 20-30% of students in a class of 300 will have issues. Common fixes: wrong Python version selected, Python not added to PATH on Windows, Mac permission issues. The bonus section below addresses most of these.

Practice

Setup verification checklist:

• Python installed (run python3 --version to confirm)
• VS Code installed and opened
• Python extension installed in VS Code
• Python interpreter selected
• Created a file called hello.py
• Successfully ran print("Hello from VS Code!") and saw output

Part 3: The Python Interactive Shell (REPL) (30 minutes)

Explanation

Python has a secret superpower for learners: the interactive shell (also called the REPL - Read, Evaluate, Print Loop).

Think of it as a calculator that speaks Python. You type one line of Python, press Enter, and immediately see the result. It's perfect for experimenting and trying out ideas quickly.

The >>> symbol is the Python prompt. It means "Python is waiting for your input."

You can open the Python shell in two ways:

1. In your terminal: type python3 and press Enter
2. In VS Code: use the Python Interactive window

Examples

# Start the Python shell (in terminal, type: python3)
# You'll see:
# Python 3.11.4 (default, ...)
# Type "help", "copyright", "credits" or "license" for more information.
# >>>
 
# Now you can type Python and see results immediately:
 
>>> 2 + 2
4
 
>>> 10 * 5
50
 
>>> "Hello" + " " + "World"
'Hello World'
 
>>> 100 / 4
25.0
 
>>> print("This works in the shell too!")
This works in the shell too!

Exiting the shell:

>>> exit()
# or press Ctrl+D (Mac/Linux) or Ctrl+Z then Enter (Windows)

When to use the shell vs. a .py file:

Common Question: "Why does the shell show a result without print(), but my .py file doesn't?" In the shell, Python automatically shows the result of every expression. In a .py file, you must explicitly use print() to display output.

# In the shell:
>>> 5 + 3
8          # Shown automatically
 
# In a .py file:
5 + 3      # Nothing shown - calculation done but discarded
print(5 + 3)   # 8 - shown because you asked for it

Practice

Shell exploration (5 minutes): Open the Python shell and try these:

>>> 365 * 24       # Hours in a year
>>> "Python" * 3   # What happens when you multiply a string?
>>> type(42)       # What type of thing is 42?
>>> type("hello")  # What type of thing is "hello"?

Write down what you see. We'll explain type() in Course 2!

Part 4: Hands-on Practice (30 minutes)

Exercise 1: The Setup Gauntlet

Complete all steps and check them off. Don't skip ahead - each step must work before moving to the next.

Step 1: Open Terminal/Command Prompt
         Run: python3 --version
         Result: _____________ (write the version number)

Step 2: Open VS Code
         Create a file: my_first_program.py
         Type: print("My name is [your name]")
         Run the file
         Result: _____________ (take a screenshot or write what you see)

Step 3: Open the Python Shell
         In terminal, type: python3
         Calculate: 365 * 24 * 60 * 60
         Result: _____________ (seconds in a year!)
         Type: exit()

Exercise 2: Customizing VS Code (Optional but Recommended)

Make VS Code more comfortable for long coding sessions:

1. Change the theme:

   • Press Ctrl+K Ctrl+T (Windows) or Cmd+K Cmd+T (Mac)
   • Try "Dark+" (popular choice), or browse themes
   • Pick what's comfortable for your eyes

2. Increase font size:

   • Go to File → Preferences → Settings
   • Search for "font size"
   • Try size 16 (bigger is better when you're starting)

3. Install "Rainbow Brackets" extension:

   • In Extensions, search "Rainbow Brackets"
   • This color-codes your brackets to prevent common errors

Bonus Challenge

For fast learners: Try these Python shell experiments and document what you discover:

>>> print("Ha" * 10)
>>> print("I am learning Python" + "!")
>>> 2 ** 10
>>> 17 % 5
>>> len("Hello, World!")

Write a one-sentence explanation of what each line does based on the output you see. Bring your explanations to discuss in Lesson 3!

Key Takeaways

• Python 3 is the current version - always use Python 3, not Python 2
• VS Code is a professional code editor that makes writing Python much easier
• When installing Python on Windows, always check "Add Python to PATH"
• The Python shell (REPL) lets you run Python commands interactively - great for experiments
• Use python3 --version to verify your installation
• Python files end in .py extension

Common Mistakes to Avoid

• Forgetting "Add Python to PATH" on Windows: This causes the python command to not be found. Solution: reinstall Python and check that box.
• Using Python 2 by accident: Always check python3 --version, not just python --version.
• Not saving the file before running: VS Code has an "autosave" option - enable it in File → Auto Save.

Troubleshooting Guide

"'python' is not recognized as an internal or external command" (Windows):

• Python wasn't added to PATH during installation
• Fix: Reinstall Python and check "Add Python to PATH"
• Alternative fix: Run the Python installer again, choose "Modify", and add to PATH

"Permission denied" when installing (Mac):

• Try running with sudo: sudo python3 setup.py install
• Or download from python.org instead of using Homebrew

VS Code can't find Python interpreter:

• Press Ctrl+Shift+P → "Python: Select Interpreter"
• Browse to the Python 3 installation manually
• On Mac it's usually: /usr/local/bin/python3
• On Windows it's usually: C:\Users\YourName\AppData\Local\Programs\Python\Python311\python.exe

Homework / Self-Study

1. Practice: Open VS Code and create a file called practice.py. Write 5 different print() statements - make them say something about yourself (your name, your hobby, your favorite food, etc.). Run the file and make sure it works.

2. Customize: Spend 10 minutes customizing VS Code (theme, font size). A comfortable environment matters for long study sessions.

3. Explore: In the Python shell, try multiplying a word by a number (e.g., "hello" * 5). What happens? Try a few variations. Come prepared to explain what you observed.

Next Lesson Preview

In Lesson 3: Your First Python Program, we'll:

• Understand the exact structure of a Python program
• Learn how Python reads and executes code
• Write our first multi-line program
• Learn about syntax errors and how to read them
• Build a program that actually does something useful

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