LESSON 02 / 12

What Is a Program?

A program is a list of instructions that tells a computer exactly what to do, step by step — a lot like a recipe.

🎓Beginnerlevel
⏱️12 minto finish
✏️5activities

📂 Computational Thinking & Pseudocode🏷️ Computational thinking

🎯 By the end of this lesson you can…

  • Explain what a program is
  • Compare a program to a recipe
  • Explain why the order of instructions matters
  • Read a short program and say what it does

A recipe for a computer

Think of your favourite recipe. It lists steps in order: mix this, add that, bake for 12 minutes. If you follow the steps, you get cookies. 🍪

A program is exactly that — but for a computer. It is a list of instructions that the computer follows, in order, to get a result.

A cookie recipe card next to a short pseudocode program
A recipe and a program: both are ordered steps that produce a result.
📘 New termProgram

A list of instructions, written in order, that tells a computer what to do.

1BEGIN2    DISPLAY "Hello!"3END

🍎 A recipe card: follow the steps, get the dish.

One step at a time, top to bottom

A computer runs a program one instruction at a time, starting at the top and moving down. It never skips ahead and never jumps back on its own (later you’ll learn instructions that tell it to repeat or choose).

greeting.pseudo 👆 Tap a line to explain it 
1BEGIN2    DISPLAY "Good morning!"3    DISPLAY "Time for school."4    DISPLAY "Have a great day!"5END

Order matters

Here are the same four steps for getting dressed, in two different orders. Which one works?

Same steps, different order
Order AOrder B
1. Put on socks1. Put on shoes
2. Put on shoes2. Put on socks
3. Tie laces3. Tie laces

Order A works. Order B puts socks on over your shoes! 😂 Programs are the same: the right steps in the wrong order give the wrong result.

🧮 Trace table — follow the program

Run the program in your head, one line at a time. Fill every empty box, then press Check.

1BEGIN2    SET SCORE = 03    SET SCORE = SCORE + 104    SET SCORE = SCORE + 55    DISPLAY SCORE6END

Check your understanding

💡 Concept check
What is a program?
🔮 What will this display?
In what order will the letters appear on the screen?
1BEGIN2    DISPLAY "C"3    DISPLAY "B"4    DISPLAY "A"5END
🐞 Find the error
This program should show “Ready”, then “Set”, then “Go!”. What is wrong?
1BEGIN2    DISPLAY "Go!"3    DISPLAY "Ready"4    DISPLAY "Set"5END
✏️ Write the pseudocode
Write a program that displays your name, then your favourite food, then your favourite colour — each on its own line.

📌 Key takeaways

  • A program is an ordered list of instructions for a computer.
  • Like a recipe, the steps must be clear and in the right order.
  • The computer runs the instructions one at a time, from top to bottom.
  • Changing the order of steps can change the result — or break it.

Finished reading & practising?

Saved in this browser. Create a free account to keep it forever.