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Setting Up Python on Windows

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Step 1 — Install Python

We recommend Python 3.13+ for the best experience. Python 3.13 has dramatically better error messages that explain what went wrong in plain English, making debugging much easier for beginners.

  1. Download Python from Python releases for Windows.
  2. Run the installer.
  3. Check Add Python to PATH — this is critical.
  4. Click Install Now.

Open PowerShell and verify:

python --version
python -c "print('hello from python')"

Expected output:

Python 3.x.x
hello from python

Step 2 — Install an editor

Option A (recommended): VS Code

Install VS Code, then add these extensions:

Option B (absolute beginners): Thonny

Thonny is a Python IDE designed for beginners. It comes with Python built in, has a simple interface, and includes a debugger that lets you step through code line by line. If VS Code feels overwhelming, start with Thonny and switch to VS Code later.

Step 3 — Create your learning folder

mkdir $HOME\Documents\python_sme
mkdir $HOME\Documents\python_sme\projects
mkdir $HOME\Documents\python_sme\templates
mkdir $HOME\Documents\python_sme\notes

uv is a modern, fast replacement for pip and venv. It is used throughout this curriculum.

powershell -ExecutionPolicy ByPass -c "irm https://astral.sh/uv/install.ps1 | iex"
uv --version

Expected output: uv x.x.x (version number).

If you prefer pip: All uv commands in this curriculum have pip equivalents. Replace uv venv with python -m venv .venv and uv pip install with pip install. Everything else stays the same.

Step 5 — Create first project and virtual environment

cd $HOME\Documents\python_sme\projects
mkdir hello_sme
cd hello_sme
uv venv
.\.venv\Scripts\Activate.ps1
python --version

Expected output:

  • Prompt starts with (.venv).
  • Python version prints.

pip fallback: Replace uv venv with python -m venv .venv.

Step 6 — Install pytest and run sanity checks

uv pip install pytest
pytest --version

pip fallback: Replace uv pip install pytest with python -m pip install pytest.

Expected output: pytest version is displayed.

Step 7 — Create first script and first test

Create hello.py:

print("Hello, Future Python SME")

Create test_hello.py:

def test_math_baseline():
    assert 1 + 1 == 2

Run:

python hello.py
pytest -q

Expected output:

Hello, Future Python SME
1 passed

Step 8 — Credential handling

Do not embed database credentials in scripts. Use environment variables:

setx APP_DB_HOST "your-sql-host"
setx APP_DB_NAME "your_db"
setx APP_DB_USER "your_sql_login"

Rules: keep passwords/tokens out of source code. Keep .env and secret files in .gitignore. Prefer approved enterprise secret storage when available. Use least privilege and read-only credentials first.

Expected output

After completing this guide you should have:

  • A working hello_sme project with hello.py, test_hello.py, and .venv.
  • python hello.py succeeds.
  • pytest -q succeeds.
  • You can explain your credential safety rules.

Troubleshooting

  • python not found: Reopen PowerShell. Confirm install finished. Reinstall and ensure "Add to PATH" is checked.
  • Activate.ps1 blocked: Run Set-ExecutionPolicy -ExecutionPolicy RemoteSigned -Scope CurrentUser in PowerShell.
  • uv not found: Re-run the install command from Step 4. Or fall back to pip.
  • pytest not found: Confirm venv is active. Run uv pip install pytest (or pip install pytest).

Break/fix drills

  1. Deactivate venv and run pytest to see failure mode.
  2. Rename test_hello.py to hello_test.py and observe discovery behavior.
  3. Intentionally misspell assert and read the traceback.
  4. Switch interpreter in VS Code, then switch back to the project venv.
  5. Add a fake credential directly in code, then remove it and replace with env var access.

Primary Sources

Optional Resources

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