1) What do I need to do?
🎯 Your mission: Rocket launch countdown
Use a for loop to count down from 10 to 1, then print Blast off!
2) What do I need to know?
Why loops?
Imagine printing "Pow!" 100 times. You could type 100 lines... or use a loop!
for i in range(5): means "do this 5 times". The lines inside are indented, just like if.
Each time round, the variable i holds the count. It starts at 0, not 1!
🧰 Your toolkit for this mission
Everything you need to know to finish this lesson on your own:
for loop
Repeat some lines a set number of times.
How to write it: for i in range(5): then indent the lines to repeat. i changes each time round.
for i in range(3):
print("Pow!")range(stop)
Counts from 0 up to but not including stop.
How to write it: range(5) gives 0, 1, 2, 3, 4.
for i in range(5):
print(i)range(start, stop)
Count from start up to stop − 1.
How to write it: range(1, 11) gives 1 to 10.
for n in range(1, 11):
print(n)range(start, stop, step)
Count in jumps. A negative step counts down.
How to write it: range(10, 0, -1) gives 10, 9, ... 1.
for n in range(10, 0, -1):
print(n)
print("Blast off!")Using the loop number
Use the loop variable in maths or text.
How to write it: Print several things with commas.
for n in range(1, 4):
print(3, "x", n, "=", 3 * n)String × number
Multiplying text repeats it.
How to write it: "#" * 3 gives ###.
for n in range(1, 4):
print("#" * n)Think about it
Look at this code. What happens next, and why? Say it in your own words.
for lap in range(3):
print("Zoom!")
print("Done")Watch & explore ▶
Power-up: Why loops?
See it happen
1 / 3for lap in range(3):
print("Zoom!")A for loop repeats the indented instruction three times.
3) Run the code & terminal output
Hero TerminalPress ▶ RUN and your program's messages appear here!
Captain Py
Our next adventure is yours to create.