Turtle Art Studio

You are the artist. Your robot turtle holds the pen and draws whatever you command. By the end of this unit you will run a spirograph design — one small shape turning into a whole design. Your mission is to discover how a short set of commands makes it.

Each idea comes as a short ladder — simplest first, then one step up — with a Notice naming the one new thing. Every turtle program here also lives in assets/ so you can run it and watch the window.

You will learn

Command the turtle to move, turn, lift its pen, and change color and pen size.
Repeat a block with a for loop and range().
Work out the turn for any polygon with 360 / n, which gives a float.
Nest one loop inside another to build a spirograph.

Lesson 1: Move the Pen

import turtle brings in the drawing tools. forward(100) moves the turtle 100 steps; right(90) turns it one square corner. The turtle draws wherever its pen touches the page.

import turtle

turtle.forward(100)
turtle.right(90)

turtle.done()

Notice

forward moves the turtle and right turns it — one move, one turn leaves an open corner.

Turtle drawings open their own window, so this program runs as a file, not in the notebook. Open a terminal in JupyterLab (File ▸ New ▸ Terminal) and move into this unit folder:

cd python-projects/units/unit-03-turtle-art-studio

Then run the file. On Windows, enter:

py assets/l1_corner.py

On a Mac, enter:

python3 assets/l1_corner.py

You can also open assets/l1_corner.py in Thonny and click Run. A drawing window opens (it may hide behind JupyterLab); close it when done.

import turtle

turtle.forward(100)
turtle.right(90)
turtle.forward(100)
turtle.right(90)
turtle.forward(100)
turtle.right(90)
turtle.forward(100)
turtle.right(90)

turtle.done()

Notice

Repeating the same move-and-turn four times draws a closed square — the turtle ends where it began.

Run assets/l1_plain_square.py the same way — a drawing window opens; close it when done.

import turtle

turtle.penup()
turtle.forward(80)
turtle.pendown()

turtle.forward(100)
turtle.right(90)
turtle.forward(100)
turtle.right(90)
turtle.forward(100)
turtle.right(90)
turtle.forward(100)
turtle.right(90)

turtle.done()

Notice

penup() lifts the pen so a move leaves no mark; pendown() drops it again before drawing.

Run assets/l1_travel.py the same way — a drawing window opens; close it when done.

import turtle

turtle.color("blue")
turtle.forward(100)
turtle.right(90)
turtle.forward(100)
turtle.right(90)
turtle.forward(100)
turtle.right(90)
turtle.forward(100)
turtle.right(90)

turtle.done()

Notice

color("blue") changes the pen color — the shape is the same, the ink is different.

Run assets/l1_color.py the same way — a drawing window opens; close it when done.

import turtle

turtle.color("teal")
turtle.pensize(4)

turtle.forward(100)
turtle.right(90)
turtle.forward(100)
turtle.right(90)
turtle.forward(100)
turtle.right(90)
turtle.forward(100)
turtle.right(90)

turtle.done()

Notice

pensize(4) makes the line thicker — a fourth pen setting, separate from color.

Run assets/l1_square.py the same way — a drawing window opens; close it when done.

Lesson 2: Repeat with `for` and `range()`

Writing the same two commands four times is a lot of typing. A for loop repeats an indented block, and range(n) runs it exactly n times. The counter starts at 0 and stops before n.

import turtle

for side in range(4):
    turtle.forward(100)
    turtle.right(90)

turtle.done()

Notice

for side in range(4): repeats the block four times — the loop replaces the written-out square.

Run assets/l2_square_loop.py the same way — a drawing window opens; close it when done.

import turtle

angle = 120
for side in range(3):
    turtle.forward(100)
    turtle.right(angle)

turtle.done()

Notice

Change range(3) and the corner turn to draw a triangle — the number of sides is now yours to choose.

Run assets/l2_triangle.py the same way — a drawing window opens; close it when done.

import turtle

n = 7
side_length = 70
angle = 360 / n
for side in range(n):
    turtle.forward(side_length)
    turtle.right(angle)

turtle.done()

Notice

Let Python compute angle = 360 / n. The / always makes a float — a decimal like 360 / 7 = 51.428… — and the turtle turns by it just the same.

Run assets/l2_polygon.py the same way — a drawing window opens; close it when done.

import turtle

n = 7
side_length = 70
angle = 360 / n

turtle.color("blue")
turtle.pensize(2)
turtle.penup()
turtle.forward(20)
turtle.pendown()

for side_number in range(n):
    turtle.pensize(side_number + 1)
    turtle.forward(side_length)
    turtle.right(angle)

turtle.done()

Notice

The loop counter side_number can do work too — here pensize(side_number + 1) makes each side a little thicker than the last.

Run assets/l2_polygons.py the same way — a drawing window opens; close it when done.

Lesson 3: Loops Inside Loops

One loop can live inside another — nested loops. The inner loop draws one whole shape; the outer loop turns the turtle and starts the next.

import turtle

for shape_number in range(2):
    for side_number in range(4):
        turtle.forward(90)
        turtle.right(90)
    turtle.right(180)

turtle.done()

Notice

The inner loop finishes a whole square before the outer loop turns 180° and starts the next — a loop inside a loop.

Run assets/l3_two_squares.py the same way — a drawing window opens; close it when done.

import turtle

for shape_number in range(6):
    for side_number in range(4):
        turtle.forward(60)
        turtle.right(90)
    turtle.right(60)

turtle.done()

Notice

More repeats with a smaller turn between them — six squares fan out into a ring.

Run assets/l3_rings.py the same way — a drawing window opens; close it when done.

Put it together: the gallery spirograph nests the same two loops, using angle = 360 / n for the shape and a small turn_between_shapes for the outer sweep. Compare the result with the spirograph promised at the start of the unit — you now know what both loops are doing.

import turtle

n = 6
side_length = 80
angle = 360 / n
shape_count = 24
turn_between_shapes = 15

turtle.color("purple")
turtle.pensize(2)

for shape_number in range(shape_count):
    for side_number in range(n):
        turtle.forward(side_length)
        turtle.right(angle)
    turtle.right(turn_between_shapes)

turtle.done()

Run assets/l3_spirograph.py the same way — a drawing window opens; close it when done.

Recap

forward, right, penup, pendown, color and pensize control the turtle's pen.
for side in range(n): repeats a block exactly n times, counting from 0.
angle = 360 / n gives the turn for an n-sided shape, and / always makes a float.
The loop counter can do work too, such as making each side thicker.
In nested loops the inner loop draws a whole shape before the outer loop turns and starts the next.

You can now design and run a spirograph of your own.

Turtle Art Studio

Lesson 1: Move the Pen

Lesson 2: Repeat with for and range()

Lesson 3: Loops Inside Loops

Lesson 2: Repeat with `for` and `range()`