Loops — making computers repeat without getting tired

⏱ 25 min build Ages 9 & 12

💡 The big idea

Loops are one of the most powerful ideas in programming. They let computers do something many times — instantly, perfectly, without complaining. Once you understand loops, you can automate almost anything.

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Two types of loops

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for loop

for i in range(5): print(i)

Runs a fixed number of times

while loop

x = 0 while x < 5: print(x) x = x + 1

Runs until a condition is false

🗣 Critical rule: Python uses 4 spaces of indentation (or a tab) to show which lines are INSIDE the loop. No spaces = not in the loop. Wrong spaces = Python crashes.

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Build with Claude

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Write a Python program using a for loop that counts from 1 to 10. After each number, print something funny. Explain how the loop works line by line for a 10-year-old who has never coded before.

Write a Python program that asks the user to guess a number between 1 and 10. Keep asking until they get it right. Use a while loop. Explain each line.

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Lesson quiz — test yourself!

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Wrap-up discussion questions

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1️⃣ What does range(5) produce? Does it start at 0 or 1?

2️⃣ What is the difference between for and while loops?

3️⃣ Why are the indentation spaces so important in Python?