Day 12: Parameters and Return Values

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.
• AAP-3.C: Develop procedural abstractions to manage complexity in a program by writing procedures.

Essential Questions

• How do parameters make functions more versatile and reusable?
• How do return values allow functions to provide results to the rest of the program?

Materials Needed

• Presentation slides on parameters and return values
• Programming environment
• Function design worksheet
• Parameter and return value exercises
• Exit ticket templates

Vocabulary

• Parameter
• Argument
• Return value
• Pass
• Function call
• Function signature
• Input
• Output
• Scope

Procedure (50 minutes)

Opening (8 minutes)

1. Review and Connection (3 minutes)

   • Review basic function concepts from previous lesson
   • Connect to today's focus on making functions more versatile with parameters and return values

2. Warm-up Activity (5 minutes)

   • Present a simple function that performs a calculation with fixed values
   • Ask students how they might modify it to work with different values
   • Introduce the need for parameters and return values

Main Activities (32 minutes)

3. Lecture: Function Parameters and Return Values (12 minutes)

   • Define parameters as input variables of a function
   • Explain the difference between parameters and arguments:
     • Parameters are variables in the function definition
     • Arguments are values passed when the function is called
   • Demonstrate the syntax for functions with parameters:
     • PROCEDURE name(parameter1, parameter2, ...)
   • Explain how parameters make functions more versatile and reusable
   • Introduce return values:
     • Purpose of returning results from functions
     • Syntax for returning values: RETURN(expression)
     • How return values are used in the calling code
     • Assigning return values to variables: result ← functionName(args)
   • Discuss the flow of execution with parameters and return values
   • Explain how parameters and return values create function interfaces

4. Demo: Passing Arguments and Receiving Results (8 minutes)

   • Walk through examples of functions with parameters and return values
   • Demonstrate how to pass different arguments to the same function
   • Show how return values can be used in expressions or stored in variables
   • Illustrate the execution flow with parameter passing and value returning
   • Show examples of common function patterns:
     • Calculation functions that return results
     • Conversion functions
     • Validation functions that return Boolean values
     • Transformation functions that process input and return modified output

5. Hands-on: Writing Functions with Parameters and Return Values (12 minutes)

   • Students work in the programming environment
   • Guide students through creating functions with parameters and return values
   • Have students implement functions for tasks like:
     • Mathematical operations with variable inputs
     • String processing functions
     • Validation functions that return true/false
     • Conversion functions between different units or formats
   • Encourage students to test their functions with various arguments

Closing (10 minutes)

6. Activity: Creating a Function Library for Common Operations (5 minutes)

   • Students work in small groups to design a set of related functions
   • Each group focuses on a specific domain (math, string processing, etc.)
   • Groups define function signatures with parameters and return types
   • Share and discuss the function libraries
   • Highlight how well-designed functions create useful tools

7. Exit Ticket and Preview (5 minutes)

   • Students develop functions that take parameters and return values
   • Preview that next class will focus on function design and documentation

Assessment

• Formative: Quality of function implementation during hands-on activities
• Exit Ticket: Correctness and usability of functions with parameters and return values

Differentiation

For Advanced Students

• Introduce functions with multiple return paths
• Challenge them to create more complex function interfaces
• Discuss parameter passing mechanisms (value vs. reference)

For Struggling Students

• Provide function templates with parameter placeholders
• Focus on simple functions with clear inputs and outputs
• Use diagrams to illustrate parameter passing and value returning

Homework/Extension

• Complete a worksheet with parameter and return value exercises
• Create a mini-library of useful functions for a specific domain
• Research how functions are documented in professional APIs

Teacher Notes

• Emphasize that parameters and return values are what make functions truly powerful
• Watch for confusion between parameters and arguments
• Make connections to mathematical functions with inputs and outputs
• Consider using physical demonstrations to show parameter passing
• Remind students that well-designed function interfaces improve code usability