Lesson 1 of 20 · Loops

Loops — Part 1

Repeat a set of steps until a goal is reached.

What you'll learn

You will learn how loops repeat code multiple times and how range() controls how many times.

Words to know

Loop: A way to repeat the same steps multiple times without writing them again and again.
range(): Gives you a sequence of numbers (e.g. 0, 1, 2) so the loop knows how many times to run.
Repeat: To do the same thing more than once. Loops help us repeat.

Your turn

📋 Show the steps

Press ▶ Run and see what the computer says!

1Look at the 'for' line. It says: repeat the indented code a certain number of times. range(${Math.min(3 + Math.floor(n / 2), 8)}) means ${Math.min(3 + Math.floor(n / 2), 8)} times.
2The indented line (print) runs once for each number in range(). So it would print Step 1, Step 2, Step 3... up to Step ${Math.min(3 + Math.floor(n / 2), 8)}.
3Without a loop, you'd need to write ${Math.min(3 + Math.floor(n / 2), 8)} separate print() lines! Loops save you from repeating yourself.
4The 'i' variable counts which round we're on (starting from 0). That's why we write i + 1 to show Step 1 instead of Step 0.

Auto-run is on: change the code and the result updates by itself.

Auto-run

Output

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Check your understanding · 1 of 5

What does a loop do?

Check your understanding · 2 of 5

How many times does this loop run? for i in range(3): print(i)

Check your understanding · 3 of 5

What does range(5) give you?

Check your understanding · 4 of 5

Which keyword starts a loop in Python?

Check your understanding · 5 of 5

What prints? for i in range(2): print("Hi")

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