Phase 1 · Day 1 · Learn AI

Variables: named boxes for values

A variable stores a value under a name so you can reuse it later. In Python you create one with a simple assignment:

Names should be readable: use snake_case like user_name or total_price. Avoid starting with a number or using reserved words like class or print.

Creating variables

name = "Ada"
age = 28
height_m = 1.68
is_student = True

print(name)
print(age)

You do not declare types upfront in basic Python. The value you assign decides the type.

Core data types

Python has a few types you will use constantly:

str — text in quotes: "hello"
int — whole numbers: 42
float — decimals: 3.14
bool — True or False

Use type(value) to inspect a value’s type while learning.

Checking types

city = "Lagos"
year = 2026
temp = 36.5
online = False

print(type(city))   # <class 'str'>
print(type(year))   # <class 'int'>
print(type(temp))   # <class 'float'>
print(type(online)) # <class 'bool'>

Converting between types

age_text = "21"
age = int(age_text)
price = float("9.99")
label = str(100)

print(age + 1)
print(price * 2)
print("Room " + label)

int("3.5") fails. Convert decimals with float first, or use int(float("3.5")).

print(): show results

print() sends text to the console. You can print multiple values separated by commas—Python inserts spaces between them.

f-strings (formatted string literals) are the cleanest way to mix variables into text.

Printing values

product = "keyboard"
price = 49.99

print("Hello, world!")
print(product, price)
print(f"The {product} costs ${price}")

input(): talk to the user

input(prompt) shows a message and waits for the user to type something. It always returns a string—even if they type a number.

Convert with int() or float() when you need math.

Reading user input

name = input("What is your name? ")
print(f"Nice to meet you, {name}!")

age_text = input("How old are you? ")
age = int(age_text)
print(f"Next year you will be {age + 1}.")

In the browser Try It panel, input() uses a prompt dialog. On your machine it reads from the terminal.

Practice

Mini challenge: personal intro

Ask for the user’s name and favorite language, then print a one-line intro using an f-string. Example output: Ada loves Python.

challenge starter

name = input("Your name: ")
language = input("Favorite language: ")

# TODO: print an f-string intro

Interactive

Try It in the browser

Create three variables (a string, an int, and a float) and print each one. Then print a single f-string that includes all three.

Output

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Errors

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Variables, Types, Print & Input