Lesson 8 of 30

Lesson 08 — Functions are magic buttons

Title: Reuse code with def

Description: Create functions that greet people, make animal sounds, calculate points, and return answers.

Why it matters for kids: A function lets you teach Python a new command.

1. First function

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def say_hello():
    print("Hello!")
    print("Welcome to Python.")

say_hello()
say_hello()

The function does nothing until you call it.

2. Function with a parameter

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def greet(name):
    print(f"Hello, {name}!")

greet("Mia")
greet("Leo")
greet("Sam")

A parameter is information the function needs.

3. Animal sounds

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def make_animal_sound(animal, sound):
    print(f"The {animal} says {sound}!")

make_animal_sound("cat", "meow")
make_animal_sound("dog", "woof")
make_animal_sound("duck", "quack")

4. Return an answer

pythonpython

def add_points(first_score, second_score):
    return first_score + second_score

total = add_points(10, 15)

print("Total points:", total)

return sends a value back.

5. Easy examples

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def build_robot_name(color):
    return f"{color} Bot"

print(build_robot_name("Red"))
print(build_robot_name("Blue"))

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def is_winning(score):
    return score >= 100

print(is_winning(50))
print(is_winning(120))

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def print_stars(count):
    print("*" * count)

print_stars(3)
print_stars(8)

6. Mini challenge

Click each example to open it.

Example 1

Create a function that prints hello.

Example 2

Call the hello function twice.

Example 3

Create a function with one name parameter.

Example 4

Create a function that prints an animal sound.

Example 5

Create a function that adds two numbers.

Example 6

Return a robot name from a function.

Example 7

Return double of a number.

Example 8

Make a function that prints stars.

Example 9

Make a function that checks a high score.

Example 10

Make describe_pet with name and animal.