The Same Loop in Python

💡 The idea

Languages differ in punctuation, not in ideas: a loop is a loop everywhere.

• Star Blocks: repeat 4 [ forward 100 right 90 ] draws the square below.
• Python - try this on a computer at home. Line 1: import turtle
• Python line 2: for i in range(4): and the colon at the end opens the block.
• Python line 3, indented by four spaces: turtle.forward(100)
• Python line 4, indented by the same four spaces: turtle.right(90)
• Python line 5, back at the left margin: turtle.done()
• So the square brackets become a colon plus indentation, and range(4) is Python's way of saying four times.
• import turtle loads a ready-made library of drawing commands, which is why every command starts with turtle.

📘 Words to know

syntax

the punctuation and spelling rules of a language

indentation

the spaces at the start of a line, which Python uses to mark a block

library

ready-made code you import, such as turtle

range

Python's way of saying how many times to repeat

👀 Watch this

The Star Blocks square. The Python version above draws exactly the same square on a home computer.

repeat 4 [ forward 100 right 90 ]

▶ Run it below

✍️ Your turn

1. Run the Star Blocks square here and be sure you know what each part does.
2. Copy the six Python lines into a notebook, keeping the indentation exactly right.
3. Match them up: which Star Blocks word became which Python word?
4. Now write the hexagon in Star Blocks below.
5. Write the Python hexagon too: for i in range(6): then turtle.forward(80) and turtle.right(60), both indented by four spaces.
6. At home, save your file as square.py and run it with python square.py

🎯 Challenge: Write the hexagon in Star Blocks here, then write the same loop in Python in your notebook and check your indentation line by line.

repeat 6 [ forward 80 right 60 ]