Objective

The objective of this unit is to introduce you to the world of programming using the Python language. You'll learn what programming is, understand why Python is a great language to start with, and learn about the tools you'll use to write and run Python programs, including setting up your Python environment and the Visual Studio Code editor. We'll also introduce you to the Turtle graphics library, a fun tool for creating graphical programs and learning programming concepts. By the end of this unit, you'll have written your first Python program and used Turtle to draw shapes!

What is Programming?

Programming is the process of creating a set of instructions that computers can understand to perform specific tasks. It's like giving a recipe to a computer: we provide step-by-step instructions, and the computer executes each step in order to achieve the final result.

Introduction to Python

Python is a popular high-level programming language known for its readability and simplicity. High-level means it's closer to human language and farther from machine language (the 1's and 0's that computers do understand to execute tasks). Python is a great language for beginners due to its straightforward syntax and a large library of tools and modules to help create diverse projects.

Setting up Your Python Environment and VS Code Editor

First, we need to install Python on your machine. Visit the official Python website and download the version suitable for your operating system. We'll also use the Visual Studio Code (VS Code) editor for writing and running our Python programs.

  1. Download and install the latest version of Python from the official Python website.
  2. Download and install VS Code from the official VS Code website.
  3. Once VS Code is installed, add the Python extension for VS Code from the marketplace by following these steps:
    • Open VS Code
    • Click on the Extensions view icon on the Sidebar (shortcut: Ctrl+Shift+X on Windows/Linux or Cmd+Shift+X on macOS)
    • Type 'Python' into the search bar
    • Select the Python extension offered by Microsoft and click Install

Writing and Running Your First Python Program

Let's write your first Python program.

  1. Launch Visual Studio Code.
  2. Click on the 'File' menu option in the top left corner of the screen, and then click on 'New Text File' (Shortcut: Ctrl+N on Windows/Linux or Cmd+N on macOS). This will open a new, blank file.
  3. Click on the 'File' menu option again, but this time click 'Save As'. Name the file "hello.py" and choose where you want to save it. Make sure to include the '.py' at the end of the file name so VS Code knows it's a Python file. (Shortcut: Ctrl+Shift+S on Windows/Linux or Cmd+Shift+S on macOS)
  4. Next, in the center editor write the following line: 
    print("Hello, world!")
    This is a simple program that, when run, will output the text "Hello, world!".
  5. Make sure to periodically save your work. Click on the 'File' menu option and click 'Save'. (Shortcut: Ctrl+S on Windows/Linux or Cmd+S on macOS)
  6. To run your code, find the green play button at the top right of the screen and click it. This button tells VS Code to run the file that's currently open.
  7. Look at the 'Terminal' panel at the bottom of the screen. You should see "Hello, world!"

Congratulations, you've successfully run your first Python program!

Introduction to the Turtle Library

The Turtle library is a graphics toolkit in Python that allows for the creation of intricate shapes and designs. You control a cursor, or "turtle", that moves around the screen to draw lines and shapes.

By adding import turtle at the top of your Python file, you can start using the Turtle library.

Let's try a simple example. In VS Code, create a new Python file named "move_turtle.py" and write the following code:

import turtle

# Create a new turtle screen and set up the window
screen = turtle.Screen()

# Create a new turtle and assign it to a variable called "t"
t = turtle.Turtle()

# Set the turtle speed to the slowest setting to see it move
t.speed(1)

# Make the turtle draw a line by moving forward 100 units
t.forward(100)

# We're done, so let's wait until the window is closed
# Note: we're calling turtle.done() and not t.done() here. We'll
# explain why in future lessons.
turtle.done()

When you run this program you should see a window open up with a little arrow (turtle) drawing a line from left to right. The window will remain open until you close it by clicking on the x button at the top of the widow.

Note: Even though it appears that nothing else is happening after the line is drawn, the program is still running and will continue to run as long as the window is open. Make sure to close the window to end the program.

If you make a change and try to run the new code while the window is open, the new code will not execute until the current window is closed.

Project: Draw a Square Using the Turtle Library

For this first project, let's use the Turtle library to draw a square. It's not very different from the code we wrote that drew the line. Look at the code below and see if you can guess what it is doing.

Create a new Python file named "draw_square.py" and write the following code.

import turtle

# Set up the window and its attributes
screen = turtle.Screen()

# Create a new turtle and assign it to a variable called "t"
t = turtle.Turtle()

# Draw the square
for _ in range(4):
    t.forward(100)   # Move forward by 100 units
    t.right(90)      # Rotate the turtle direction clockwise by 90 degrees

# We're done, so let's wait until the window is closed
turtle.done()

This program draws a square by making the turtle move forward by 100 units, then turn right by 90 degrees, four times over. The result is a perfect square.

Remember, programming is about consistent learning and practice. Don't get discouraged if things don't make sense initially; your understanding will improve over time. Keep at it, and have fun coding!

In the next unit, we'll explore variables and data types.