👋 Welcome Back to Mr. Ken’s Code School!

Hello, young coder! 🧒👧 Today, let’s go on a magical journey into a house — not just any house, but a Python House 🐍 where your computer programs live!

This house is full of rooms 🛏️, people 👨‍👩‍👧, and — you guessed it — toys! But not all toys are the same. Some toys are for everyone in the house, while others are only for certain rooms.

Let’s step inside and see how this works…

🎁 Meet the Toys — a.k.a Variables

In the world of Python programming, a variable is like a toy — it holds something special. Maybe it’s a number, a word, or even a game score.

But just like in a real house, where you put the toy matters a lot!

🛋️ Living Room Toys – Global Variables

Living Room Rule: Toys in the living room are for everyone in the house!

Let’s say you have a toy called age, and you leave it in the living room. Anyone — whether it’s Mom in the kitchen, Dad in the study, or you in your room — can come to the living room and play with age.

In Python, this is what we call a global variable. It’s a variable you create outside any function, right there in the main part of your program.

Here’s how it looks:

age = 8  # This is a global variable

def say_age():
    print(age)  # This function can see the global variable!

say_age()

What happens here? When say_age() runs, it goes to the living room and finds the toy called age. Perfect! Everyone can access it.

🛏️ Bedroom Toys – Local Variables

Bedroom Rule: Toys in your bedroom are only for you.

Now imagine you got a secret toy robot and you keep it under your pillow in your bedroom. It’s your little secret! No one else in the house knows it’s there — unless they sneak into your room (which isn’t allowed in Python world!).

In Python, when you create a variable inside a function, it becomes a local variable. It can only be used inside that function — like a toy kept in your room.

def my_room():
    secret_toy = "robot"
    print(secret_toy)  # Works fine here

my_room()

print(secret_toy)  # ❌ Error! Can't find the toy outside the room!

Oops! The computer says: “I don’t know what secret_toy is!” Why? Because secret_toy is locked inside the function my_room() — just like your toy robot hidden in your bedroom.

🧪 But Wait… What if We Try to Change a Living Room Toy from the Bedroom?

Let’s say you have a toy called age in the living room. But then, inside your bedroom, you say:

age = 10

Now what happens? 🤔

In Python, if you assign a new value to a variable inside a function, Python assumes you’re creating a new local toy, not using the one from the living room.

So unless you tell Python “Hey, I want to use the global toy!”, it won’t touch the one outside.

Here’s an example:

age = 8  # Global toy

def change_age():
    age = 10  # This creates a NEW toy in the bedroom!
    print("Inside room:", age)

change_age()
print("In the living room:", age)

Output:

Inside room: 10
In the living room: 8

See? The living room toy is untouched! If you really want to change the global one, you must declare:

def change_age():
    global age
    age = 10

🏁 Summary Time!

Here’s a quick wrap-up of our journey through the Python House:

Room Variable Type Who Can Use It?
🛋️ Living Room Global Everyone (outside and inside functions)
🛏️ Bedroom (inside function) Local Only the function/room where it was created

🧠 Let’s Review!

1. What is a global variable in Python?

2. What is a local variable in Python?

3. What happens if you try to use a local variable outside its function?

4. Can a function change a global variable without using the global keyword?

5. Why is it important to know where your “toys” (variables) are in your program?

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