Answer: Turtle Challenge #368

Here’s what the code from Turtle Challenge #368 draws. This picture was made by running the code for real.

The answers

Will the lines get longer or shorter? Longer! i goes up by 1 each time, so i * 3 makes every line 3 steps longer than the one before.

What shape does the spiral look like? It’s based on a triangle, because 119 degrees is close to 120. Because 119 is just a little less than 120, every corner is slightly off, so the spiral slowly twists round like a whirlpool.

How many colours will you see? 4: deeppink, red, royalblue, purple. i % 4 picks the next colour in the list each time.

How the code works

The loop runs 50 times. Each line is longer than the last, and the turtle turns 119 degrees after each one, so the lines wind outwards.

import turtle

t = turtle.Turtle()
t.speed(0)
turtle.bgcolor("black")
colours = ["deeppink", "red", "royalblue", "purple"]

for i in range(50):
    t.pencolor(colours[i % 4])
    t.forward(i * 3)
    t.left(119)

t.hideturtle()
turtle.done()