Code Labs: Core Constructs

Put Sequence, Selection, and Iteration into practice using Python.

Interactive Engine

Write Python code directly below. Press Run Code to compile your algorithms locally inside your browser.

> Waiting to compile...

The Crucible

Prove your knowledge of the 3 fundamental programming constructs.

Bronze (Sequence)

The Chronology Crash

This programme triggers a massive NameError! The code is executing sequentially from top to bottom, but we are trying to output a variable before we even ask the user for it.

Task: Rearrange the lines of code so that it runs perfectly. The final line must print the favourite_colour variable.

> Output will appear here...
Silver (Selection)

The Bouncer's Logic

This cinema ticket system has a strict age rating of 15. The code attempts to use an IF/ELSE statement to branch the logic based on the user's age, but it has a lethal syntax error preventing it from running.

Task: Locate the missing punctuation and fix the comparison operator (the user must be 15 or over to watch the movie). The console must print Watch Move or Go Home.

> Output will appear here...
Gold (Iteration)

The Infinite Loop Trap

You have been tasked with building an alarm countdown. You need to use a WHILE loop (condition-controlled iteration).

Task: Write a loop that prints the numbers 5, 4, 3, 2, 1 and then prints ALARM. Your loop MUST subtract 1 from the timer each time, otherwise you will crash your browser by creating an infinite loop!

timer = 5
while ( ... ):
  print(timer)
  timer = timer - 1
print("ALARM")
> Output will appear here...