Turtle Graphics

Introduction

Turtle Graphics is one of the most exciting ways to learn Python programming visually. The turtle module comes built into Python's standard library, so no installation is needed. It provides a virtual turtle that moves around the screen, leaving a trail (pen) behind it to create drawings.

Turtle graphics is an excellent starting point for understanding coordinate systems, loops, functions, and modular programming. It is also a frequently asked topic in university practical exams.

What is Turtle Graphics?

Turtle Graphics works by controlling a virtual "turtle" on the screen. The turtle has:

• A position (x, y coordinates on the screen)
• A direction (heading — which way it's facing)
• A pen that can be up or down (drawing or not drawing)
• A color, speed, and shape

The default screen is 400x300 pixels with the turtle starting at the center (0, 0). The x-axis goes from left (-200) to right (200), and the y-axis goes from bottom (-150) to top (150).

Real-life Analogy: Imagine placing a pen on a piece of paper and commanding it to move forward, turn left, move again, etc. The trail left by the pen creates the drawing — this is exactly how turtle graphics works.

Importing and Setting Up

There are several ways to import and use the turtle module:

# Method 1: Import the entire module
import turtle

# Method 2: Import with an alias
import turtle as t

# Method 3: Import specific functions
from turtle import *

# Create a screen (optional)
screen = turtle.Screen()
screen.title("My Turtle Program")
screen.bgcolor("white")
screen.setup(width=600, height=500)

# Create a turtle object
pen = turtle.Turtle()
pen.shape("turtle")
pen.color("blue")

Movement Commands

These are the core commands to move the turtle around the screen:

import turtle

t = turtle.Turtle()

# Move forward and turn
t.forward(100)    # Draw a line 100 pixels long
t.right(90)       # Turn 90 degrees right
t.forward(100)    # Draw another line

# Check position
print(t.pos())    # (100.00, -100.00)
print(t.heading())  # 270.0 (facing South)

turtle.done()

Pen Control Commands

Pen control determines whether the turtle draws as it moves and the appearance of the drawn lines:

import turtle

t = turtle.Turtle()
t.speed(3)         # Moderate speed
t.pensize(3)       # Thick pen
t.pencolor("blue") # Blue lines

# Draw a filled square
t.fillcolor("yellow")
t.begin_fill()
for _ in range(4):
    t.forward(100)
    t.right(90)
t.end_fill()

turtle.done()

Turtle Appearance

You can customize how the turtle looks on screen:

import turtle

t = turtle.Turtle()

# Shape: "arrow", "turtle", "circle", "square", "triangle", "classic"
t.shape("turtle")

# Color of the turtle shape
t.color("green")

# Hide the turtle cursor
t.hideturtle()

# Show the turtle cursor again
t.showturtle()

# Stamp a copy of the turtle shape at current position
t.stamp()

turtle.done()

Examples with Output

import turtle

t = turtle.Turtle()
t.forward(200)  # Draws a horizontal line from center to the right

turtle.done()
# Output: A single horizontal blue line of 200 pixels

import turtle

t = turtle.Turtle()
t.pensize(2)
t.pencolor("red")

for _ in range(3):
    t.forward(150)
    t.left(120)

turtle.done()
# Output: An equilateral triangle drawn with red lines

import turtle

t = turtle.Turtle()
t.color("black", "lightblue")  # pen color, fill color
t.begin_fill()

for _ in range(2):
    t.forward(200)
    t.left(90)
    t.forward(100)
    t.left(90)

t.end_fill()
turtle.done()
# Output: A filled lightblue rectangle (200x100 pixels)

import turtle

t = turtle.Turtle()
t.speed(5)
t.pensize(3)
t.pencolor("darkgreen")

t.circle(80)     # Circle with radius 80
t.penup()
t.forward(200)
t.pendown()
t.circle(40)     # Smaller circle with radius 40

turtle.done()
# Output: Two circles — a large one and a smaller one to the right

import turtle

t = turtle.Turtle()
t.speed(8)
t.pensize(2)
t.pencolor("purple")
t.hideturtle()

for _ in range(5):
    t.forward(150)
    t.right(144)

turtle.done()
# Output: A five-pointed star drawn in purple

import turtle

t = turtle.Turtle()
t.speed(5)

# Draw an "L" shape using coordinates
t.penup()
t.goto(-100, -100)
t.pendown()
t.goto(-100, 100)   # Vertical line up
t.goto(-50, 100)    # Horizontal line right

# Move to another position
t.penup()
t.goto(50, -100)
t.pendown()
t.goto(50, 100)     # Vertical line
t.goto(100, 100)    # Horizontal line

turtle.done()
# Output: Two L-shaped figures on the screen

import turtle

t = turtle.Turtle()
t.speed(5)

for _ in range(4):
    t.forward(100)
    t.penup()
    t.forward(20)     # Gap — no drawing
    t.pendown()

turtle.done()
# Output: A square with gaps at each corner

Key Points

Practice Questions

Summary