Functions

Learning objectives

• Use a for loop
• Write a function without an argument and without a return type
• Write a function that calls a function
• Write a function that requires an argument
• Write a function with a return value

For teachers

Teaching goals are:

• Learners have used a for loop
• Learners have written functions

Lesson plan:

• 5 mins: prior knowledge
• 5 mins: presentation
• 15 mins: challenge
• 5 mins: feedback

Prior:

• What are functions?
• Why use functions?
• Can you name some Python functions?

Overview

Sometime you need to do a same multi-line calculation multiple times in your code. Instead of copy-pasting, one can use a so-called 'function' to bundle a calculation is something that can be reused.

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Exercises

See the exercise procedure here.

Exercise 1: using a for loop

Learning objectives

• Use a for loop

Read the following sections of How to Think Like a Computer Scientist: Learning with Python 3:

• 3.2. Instances — a herd of turtles
• 3.3. The for loop
• 3.4. Flow of Execution of the for loop
• 3.5. The loop simplifies our turtle program

Then do exercise

• 3.8.1
• 3.8.5

Exercise 2: a simple function

Learning objectives

• Write a function without an argument and without a return type

Read the following sections of How to Think Like a Computer Scientist: Learning with Python 3:

• 4.1. Functions

Then do exercise:

• 4.9.1

Exercise 3: write a function that calls a function

Learning objectives

• Write a function that calls a function

Read the following sections of How to Think Like a Computer Scientist: Learning with Python 3:

• 4.2. Functions can call other functions

Then do exercise:

• 4.9.2

Exercise 3: write a function that requires an argument

Learning objectives

• Write a function that requires an argument

Read the following sections of How to Think Like a Computer Scientist: Learning with Python 3:

• 4.4. Functions that require arguments

Then do exercise:

• 4.9.3

Exercise 4: write a function with a return value

Learning objectives

• Write a function with a return value

Read the following sections of How to Think Like a Computer Scientist: Learning with Python 3:

• 4.5. Functions that return values

Then do exercise:

• 4.9.7
• 4.9.8

Links

• How to Think Like a Computer Scientist: Learning with Python 3