Lesson 11 of 12

Functions 🔧

🎯 Grades 6–8 ⏱ ~25 minutes 💚 Intermediate

What You'll Learn

Define and call functions
Use parameters and return values
Break a program into reusable pieces

What Is a Function?

A function is a reusable block of code you give a name. Instead of copying the same code in multiple places, you write it once as a function and call it whenever you need it.

Python

# Define the function
def greet():
    print('Hello!')
    print('Welcome to OKSTEM!')

# Call it as many times as you want
greet()
greet()

Parameters and Arguments

Parameters are variables that receive data when the function is called:

Python

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

greet('Alex')    # Hello, Alex!
greet('Jordan')  # Hello, Jordan!

Return Values

Python

def add(a, b):
    result = a + b
    return result

total = add(5, 3)
print(total)  # 8
print(add(10, 20))  # 30

💡

Return vs Print

A function that prints shows output but nothing comes back. A function that returns gives back a value you can use in more calculations.

🔧">Mini Calculator Functions

Write four functions: add(a, b), subtract(a, b), multiply(a, b), divide(a, b). Each should return the result. Then build a menu that asks which operation to use.

Quick Check

What keyword starts a function definition?

Afunction

Bdefine

Cdef

What does return do in a function?

APrints the result to screen

BSends a value back to the caller

CStops the whole program

What are the variables in the parentheses of a function definition called?

AReturns

BParameters

CArguments