Turtle Graphics Programs

Introduction

After learning the basic turtle commands, it is time to apply them in real programs. This chapter presents a collection of practical turtle graphics programs that are commonly asked in university practical exams and competitive programming assessments.

Each program includes the complete code, a step-by-step explanation, and a description of the expected output. Practice typing these programs yourself to build muscle memory and deepen your understanding.

Program 1: Draw a Square

import turtle

t = turtle.Turtle()
t.speed(5)
t.pensize(2)
t.pencolor("blue")

# Draw a square
for _ in range(4):
    t.forward(150)
    t.right(90)

turtle.done()

Step-by-Step Explanation

• import turtle — imports the turtle module.
• t = turtle.Turtle() — creates a turtle object named t.
• t.speed(5) — sets moderate drawing speed.
• The for loop runs 4 times: move forward 150 pixels, then turn right 90 degrees.
• After 4 iterations, the turtle returns to its starting position, completing the square.

Output: A blue square of side 150 pixels drawn in the center of the screen.

Program 2: Draw a Circle

import turtle

t = turtle.Turtle()
t.speed(8)
t.pencolor("darkred")
t.fillcolor("pink")

t.begin_fill()
t.circle(100)
t.end_fill()

turtle.done()

Step-by-Step Explanation

• t.fillcolor("pink") — sets the interior color to pink.
• t.begin_fill() — starts recording the shape vertices.
• t.circle(100) — draws a circle of radius 100 pixels.
• t.end_fill() — fills the enclosed area with pink.

Output: A pink-filled circle with a dark red border drawn from the bottom-center point.

Program 3: Draw a Five-Pointed Star

import turtle

t = turtle.Turtle()
t.speed(7)
t.pensize(2)
t.pencolor("gold")
t.fillcolor("yellow")

t.begin_fill()
for _ in range(5):
    t.forward(200)
    t.right(144)
t.end_fill()

t.hideturtle()
turtle.done()

Step-by-Step Explanation

• A five-pointed star has 5 sides, each turned at an exterior angle of 144 degrees (360/5 = 72, exterior = 180 - 72 = 144).
• The loop runs 5 times: move forward 200 pixels, turn right 144 degrees.
• begin_fill() and end_fill() fill the star with yellow.
• hideturtle() hides the turtle cursor for a cleaner look.

Output: A yellow-filled five-pointed star with a gold border.

Program 4: Draw a Spiral

import turtle

t = turtle.Turtle()
t.speed(0)   # Fastest speed
t.pensize(1)

colors = ["red", "orange", "yellow", "green", "blue", "purple"]

for i in range(120):
    t.pencolor(colors[i % 6])
    t.forward(i * 2)
    t.right(61)   # Slightly more than 60 degrees

t.hideturtle()
turtle.done()

Step-by-Step Explanation

• The loop runs 120 times, each time increasing the forward distance by i * 2 pixels.
• colors[i % 6] cycles through 6 colors using the modulus operator.
• Turning 61 degrees (slightly more than 60) creates a spiraling effect instead of a closed hexagon.
• With speed(0), the drawing completes quickly.

Output: A colorful spiral that grows outward from the center, cycling through rainbow colors.

Program 5: Draw a House

import turtle

t = turtle.Turtle()
t.speed(5)
t.pensize(3)

# --- Draw the base of the house (rectangle) ---
t.pencolor("brown")
t.fillcolor("lightyellow")
t.begin_fill()
for _ in range(2):
    t.forward(200)
    t.left(90)
    t.forward(150)
    t.left(90)
t.end_fill()

# --- Draw the roof (triangle) ---
t.pencolor("darkred")
t.fillcolor("red")
t.begin_fill()
t.left(90)           # Face upward
t.forward(150)       # Move to top-left corner
t.right(150)         # Angle for roof slope
t.forward(115)       # Right side of roof
t.right(60)          # Complete the triangle
t.forward(115)       # Back to top-left
t.left(30)           # Reset heading
t.end_fill()

# --- Draw the door (small rectangle) ---
t.penup()
t.goto(60, -75)
t.pendown()
t.pencolor("brown")
t.fillcolor("sienna")
t.begin_fill()
for _ in range(2):
    t.forward(40)
    t.left(90)
    t.forward(60)
    t.left(90)
t.end_fill()
t.end_fill()

t.hideturtle()
turtle.done()

Step-by-Step Explanation

• The base is a rectangle (200 × 150) filled with light yellow.
• The roof is a triangle drawn on top of the rectangle, filled with red.
• The door is a smaller rectangle drawn at the bottom-center of the house, filled with brown.
• penup() and goto() are used to reposition the turtle without drawing.

Output: A simple house with a yellow base, red roof, and brown door.

Program 6: Draw a Colorful Geometric Pattern

import turtle

t = turtle.Turtle()
t.speed(0)
t.pensize(2)

colors = ["red", "blue", "green", "orange", "purple", "cyan"]

# Draw 6 overlapping squares rotated at different angles
for i in range(6):
    t.pencolor(colors[i])
    for _ in range(4):
        t.forward(120)
        t.left(90)
    t.right(60)   # Rotate before drawing next square

t.hideturtle()
turtle.done()

Step-by-Step Explanation

• The outer loop runs 6 times, each time changing the pen color.
• The inner loop draws a square (4 sides × 90° turn each).
• After each square, right(60) rotates the turtle so the next square is offset by 60 degrees.
• This creates a beautiful flower-like overlapping pattern.

Output: Six overlapping squares rotated at 60-degree intervals, each in a different color, forming a star/flower pattern.

Program 7: Draw Concentric Circles

import turtle

t = turtle.Turtle()
t.speed(5)
t.pensize(2)

colors = ["red", "orange", "yellow", "green", "blue"]

for i in range(5):
    t.pencolor(colors[i])
    radius = 30 + i * 30   # 30, 60, 90, 120, 150
    t.circle(radius)

t.hideturtle()
turtle.done()

Step-by-Step Explanation

• The loop runs 5 times, each drawing a circle with an increasing radius.
• radius = 30 + i * 30 gives radii of 30, 60, 90, 120, and 150 pixels.
• Each circle is drawn in a different color.
• All circles share the same starting point, creating a concentric pattern.

Output: Five concentric circles in different colors, like a target pattern.

University Exam Tips

Practice Questions

Key Points

Summary

This chapter covered seven practical turtle graphics programs ranging from simple shapes (squares, circles) to complex patterns (spirals, concentric circles, houses). Understanding the angle formulas and loop structures is key to creating any turtle graphics program. Practice these programs and modify them with different colors, sizes, and shapes to build confidence for exams.