A program is steps in order
Press Run. Then swap two lines and run it again: the output changes because the order changed.
A program is a list of exact instructions that a computer follows in order. Almost every program takes some input, does some processing, and produces output; the text you write is called source code, and a mistake in it is called a bug.
Change the code and press Run (Ctrl+Enter). Predict what will happen first, then break it on purpose and read what changes. Your edits are saved and match the lesson page.
Ready for more? This phase has 5 hands-on exercises with automatic checks.
Practice questions
Write the code in the editor, run it, then open the model answer to compare.
Write a program that prints the three steps for brushing your teeth, one per line, in the correct order.
Write a program that remembers the prices of a pen (10) and a notebook (45), adds them, and prints Total: 55.
This program should print the cost of three pencils at 5 each, but it prints 10. Find and fix the bug: pencil = 5 then cost = pencil + pencil then print("Cost:", cost).
Explain it without notes
In your own words, what is a program?
What are the three parts that almost every program has? Give an example of each for a calculator app.
What is a bug, and why can't the computer find every bug for you?
Why does the order of statements matter?
Expected output
Boil one cup of water.
Add one spoon of tea leaves.
Wait two minutes.
Pour into a cup.