Day 11: Introduction to Functions

Learning Objectives

• AAP-3.A: For procedure calls: Write statements to call procedures.
• AAP-3.B: Explain how the use of procedural abstraction manages complexity in a program.

Essential Questions

• How do functions help us organize and reuse code?
• What is procedural abstraction and why is it important in programming?

Materials Needed

• Presentation slides on functions and procedural abstraction
• Programming environment
• Function implementation worksheet
• Code refactoring examples
• Exit ticket templates

Vocabulary

• Function
• Procedure
• Method
• Procedural abstraction
• Modularity
• Call
• Definition
• Implementation
• Reusability

Procedure (50 minutes)

Opening (8 minutes)

1. Review and Week 3 Introduction (3 minutes)

   • Review nested control structures from previous lesson
   • Introduce Week 3 focus on functions and procedural abstraction
   • Connect to today's focus on functions as a way to organize code

2. Warm-up Activity (5 minutes)

   • Present a program with repeated code segments
   • Ask students to identify the repetition and discuss problems with this approach
   • Introduce the need for code reuse and organization

Main Activities (32 minutes)

3. Lecture: Functions and Procedural Abstraction (12 minutes)

   • Define functions/procedures as named groups of programming instructions
   • Explain the concept of procedural abstraction:
     • Separating what a function does from how it does it
     • Hiding implementation details
     • Creating reusable code components
   • Discuss the benefits of using functions:
     • Code reuse
     • Readability and organization
     • Modularity
     • Easier testing and debugging
     • Collaboration
   • Introduce function terminology:
     • Definition vs. call
     • Implementation
     • Scope
   • Explain the basic structure of functions in pseudocode:
     • PROCEDURE name()
   • Discuss the flow of execution when calling functions
   • Explain how function calls interrupt sequential execution

4. Demo: Defining and Calling Functions (8 minutes)

   • Walk through examples of defining simple functions
   • Demonstrate how to call functions from different parts of a program
   • Show the execution flow when functions are called
   • Illustrate how functions can be called multiple times
   • Demonstrate how functions can make code more readable
   • Show before-and-after examples of code with and without functions

5. Hands-on: Creating Simple Functions (12 minutes)

   • Students work in the programming environment
   • Guide students through creating and using functions
   • Have students implement functions for tasks like:
     • Calculating area or perimeter
     • Converting units
     • Generating formatted output
     • Validating input
   • Encourage students to call their functions multiple times with different scenarios

Closing (10 minutes)

6. Activity: Refactoring Code to Use Functions (5 minutes)

   • Provide students with a program that has repeated code segments
   • Students refactor the code by creating appropriate functions
   • Compare the original and refactored versions
   • Discuss improvements in readability and maintainability

7. Exit Ticket and Preview (5 minutes)

   • Students write a program that uses functions to organize code
   • Preview that next class will focus on function parameters and return values

Assessment

• Formative: Quality of function implementation during hands-on activities
• Exit Ticket: Effectiveness of program organization using functions

Differentiation

For Advanced Students

• Challenge them to identify more opportunities for abstraction
• Introduce the concept of function composition
• Discuss advanced topics like recursion (preview)

For Struggling Students

• Provide function templates to complete
• Focus on simpler functions with clear purposes
• Use visual aids to illustrate function execution flow

Homework/Extension

• Complete a worksheet with function implementation exercises
• Refactor a previously written program to use functions
• Research how functions are used in professional software development

Teacher Notes

• Emphasize that functions are a fundamental concept in programming
• Watch for confusion between function definition and function call
• Make connections to mathematical functions students already know
• Consider using analogies like recipes or instruction manuals
• Remind students that good function design is key to maintainable code