Each line of Python does one thing, from the top down.
The big ideaPython is code written in words. It reads one line at a time, top to bottom.
How it works
Python is code written in words. A computer reads it one line at a time, from the top line down.
Print is a command that shows something on the screen. It needs brackets, and the text goes inside quotes.
Quotes tell Python that something is text. Print shows only what is inside the quotes.
An error message is a clue that points at the line to fix. The computer is fine.
How Python runs a program.
Example 1: One line
Zara types print("Hello") and runs it.
Print is the command, and Hello is the text inside the quotes.
Bo's screen shows the word Hello.
Example 2: Two lines
Line 1 is print("Hello"), and line 2 is print("I am Bo").
Python reads line 1 first and line 2 next.
Bo's screen shows Hello, and then I am Bo.
Example 3: A missing quote
Leo types print("Hello Leo) and forgets the last quote.
Python stops and points at the line, and the message is a clue.
The mix-up to fix: put the closing quote back, so the line reads print("Hello Leo").
Bo's screen says Hello Leo.
Example 4: A small letter p
The line Print("hello") does not work, because Python needs a small letter p in print.
The mix-up to fix: write print("hello").
Words to know
Python
A language for writing code in words.
command
A word that tells the computer to do something, like print.
text
Words inside quotes. Python shows text exactly as it is written.
error message
A clue that points at the line to fix.
Watch out
Every opening quote needs a closing quote, and every opening bracket needs a closing bracket.
Python needs a small letter p in print, so Print with a capital P is a mix-up to fix.
Without quotes, hello is not text, so print(hello) is a mix-up to fix.
An error message is not a telling-off. It is a clue.
Try it
What does print("I am Bo") show on the screen?
Which line has a mix-up to fix: print("Hi Zara") or print(Hi Zara)?
A program has two lines: print("A") and then print("B"). Which does the screen show first?
Leo writes print("Hello) and a message points at it. What is the mix-up to fix?
True or false: an error message means the computer is broken.
Answers: 1. I am Bo · 2. print(Hi Zara) · 3. A · 4. The closing quote is missing · 5. False
Try at homeAsk a grown-up to write three short instructions on paper, one per line, like clap, stamp, spin. You are the computer. Read from the top line down and do exactly what each line says, nothing more. Then swap: you write, they do.
For grown-upsIf you can run Python, type one print line together, run it, then take away one quote on purpose and read the message as a clue. If not, play the Mission: write three short instructions on paper, one to a line, and be the computer.
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