Lesson 3 of 12 · 30 min · Grades 9–12
Strings — shaping text
A school notice is text you clean: capitals for a banner, a name dropped into a sentence, a line split into words. Strings are not just print decorations — they are data. Attendance files, WhatsApp exports and log lines are strings until you parse them.
Class notice message
Strings are text you can shape.
You will be able to
- ✓ Join strings and use f-strings
- ✓ Use upper, lower and replace
- ✓ Treat text as something you can transform
f-strings fill blanks
f"Hello {name}" inserts the variable into the sentence. It stays readable when a notice has three blanks. Comma-print is fine for two values; f-strings win for prose.
The f is not decoration. Without it, {name} would print as the characters {name}. With it, Python evaluates the braces.
Methods hang on the string
"stem".upper() returns "STEM". The original string in a variable is not always changed — in real Python strings are immutable, so you store the result: banner = msg.upper().
replace(old, new) is search-and-replace for a notice. split() turns a sentence into a list of words — the start of counting word frequency, which pandas will later do in bulk.
Words that matter
- f-string
- A string prefixed with f that can include {expressions}.
- Immutable
- In real Python, string methods return new strings; they do not edit in place.
Common mistakes
Avoid: "Hello {name}" without the f prefix.
Do this: f"Hello {name}".
Example program — House announcement
Edit the house name; the sentence updates.
Edit the example, press Run, then Build if you want a compile check.
build
Press Build to compile.
Your turn — ID card line
name = "kabir". Print the name in uppercase so KABIR appears.
Edit the example, press Run, then Build if you want a compile check.
build
Press Build to compile.
Self-assessment
Check your understanding before you mark the lesson complete.
Progress is stored in a browser cookie on this device.