From blocks to Python

You have built programs with blocks and typed some Python. The good news: the ideas are the same. Here is how each block becomes a line of text.

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Matching blocks to Python

In Scratch the blocks inside a loop are wrapped in its C shape. In Python they are indented.
Scratch blockPython
say [Hello]print("Hello")
set [score] to (0)score = 0
change [score] by (1)score = score + 1
ask [Name?] and wait, then use answeranswer = input("Name? ")
repeat (10)for i in range(10):
foreverwhile True:
repeat until <done>while not done:
if < > then ... elseif condition: ... else: ...

An example

Scratch: set [score] to (0), then repeat (5) { change [score] by (2) }, then say (score).
Python:
score = 0
for i in range(5):
    score = score + 2
print(score)
Output: 10

What changes in a text language

In a text language you must get the spelling, punctuation and indentation exactly right, or you get a syntax error.
In exchange, text languages are faster to write for big programs, easier to share and search, and used by professional programmers.
Note that Python's range(10) counts 0 to 9, but it still repeats 10 times, just like repeat (10).
Worked example

A Scratch script says: set [lives] to (3), repeat until <lives = 0> { change [lives] by (-1) }, say [Game over]. Write the Python and say what it prints.

  1. set [lives] to (3) becomes lives = 3.
  2. repeat until <lives = 0> keeps going while lives is NOT 0; here we write while lives > 0:
  3. change [lives] by (-1) becomes lives = lives - 1, indented.
  4. say [Game over] becomes print("Game over"), not indented, so it runs after the loop.

Answer: lives = 3
while lives > 0:
    lives = lives - 1
print("Game over")
It prints: Game over

Key idea

Every block has a Python match: say is print, set and change use =, ask is input, repeat (n) is a for loop, forever and repeat until are while loops. In Python, indentation does the job of the block's C shape.

Key words
AND
A Boolean operator that gives True (1) only when both inputs are True.
Input
Data put into a computer, for example from a keyboard, mouse, microphone or sensor.
For loop
A count-controlled loop that repeats a set number of times.
Output
Information sent out from a computer, for example to a screen, speaker or printer.
Syntax error
A mistake in the rules of the language, such as a missing colon or bracket, so the program cannot run.

All KS3 Computing key terms and definitions →

Common mistakes
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Extra practice

2 more questions

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  1. Which Python line matches the Scratch block set [score] to (0)?

    1. score = score + 0
    2. score == 0
    3. score = 0
    4. print(score)
    Show the answer

    Answer: score = 0

    set stores a value.

  2. Which Python loop matches the Scratch block repeat (5)?

    1. while True:
    2. if i < 5:
    3. repeat 5:
    4. for i in range(5):
    Show the answer

    Answer: for i in range(5):

    range(5) runs 5 times.

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Sources and references

Last updated 2 October 2026. Spotted a mistake? Tell us and we will fix it.