Loops Make Patterns 🔁

Did you notice drawing a square meant writing the same two lines four times? Coders don't like repeating themselves. Instead, they use a loop:

import turtle
t = turtle.Turtle()

for i in range(4):
    t.forward(100)
    t.left(90)

for i in range(4): means "do the lines below 4 times."

💡

⚠️ The lines that repeat must be indented (pushed in with spaces). That's how Python knows which lines belong to the loop.

⭐ Draw a star

Turn 144 degrees, 5 times, and you get a star. Space time!

import turtle
t = turtle.Turtle()
t.color("gold")

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

🌳 Loops work for printing too

for i in range(3):
    print("Plant a tree")

That prints Plant a tree three times.

Counting with a loop

i counts for you. range(1, 4) counts 1, 2, 3 (it stops before 4):

for i in range(1, 4):
    print("Day", i)

🌲 Fun fact

Every year, people around the world plant billions of trees to grow back forests. Trees clean the air and are home to huge numbers of animals. A loop that plants a billion trees would be a very long loop!