Module 4 - Using Functions

Creating simple functions.

Before the week begins

Major Topics

• Stategies for debugging programs

• Basic syntax and idea of creating functions.

• Reading and responding to unit tests

• The difference between printing and returning

• Interpreting function scope

Materials

• week3_day1_Functions.pptx

• week3_day2_MoreFunctions.pptx

Due This Week:

• Module 2 quizzes and programming problems

• Project 1

Graded This Week

• Python Installation Activity

Student Difficulty

???

Module 3 - Staff Meeting

Note: Most TA training materials come directly from:

Luther A. Tychonievich (2017) Training Course for Teaching Assistants in Computing, <https://www.cs.virginia.edu/luther/ta-training>. Accessed 2019-02-25

• Reminders:

  • Python Installation activity must be graded this week

  • First project is due this week (Turtle graphics)

    • Grading is binary and simple - they either completed the instructions or did not. Common issues:

      • Did not draw a black border? No points.

      • Uploaded code as a screenshot? No points.

      • Uploaded code in a word doc? No points.

      • Drew a single line and gave up? No points.

  • TA Feedback Report was due on Friday

• Ethics Activity

  • Read the assignment description

  • Read the guide

  • Prompt: Net Neutrality

  • Demonstration of grading assignment through Canvas.

    • ASSIGN POINTS THROUGH THE RUBRIC, NOT AT RANDOM

• Project 2: Magical Banking

  • Context: writing an app to approve or reject loans for a magical bank

  • Need to integrate weird code from a grumpy co-worker, without touching it.

  • Main goal is to learn about program flow and satisfying unit tests

  • Write a function that calls several other functions, and also define those functions

  • Each function is individually very simple, but the combination of all of them will be challenging for some students who have not incorporated these ideas.

  • Difficulty level is higher than last project, hopefully around a 2-4 hour project for most students.

  • Expect many students to ignore the unit tests

  • Added problem: students will be using web-cat for the first time.

  • You’ll need to try it out and complete it yourselves

  • Monday Class:

    • Room organized into color groups using construction paper

    • Start with brief lecture highlighting project components

    • Students are encouraged to work together on handout assignment (function tables) and the first two functions (print_introduction and input_name)

    • Also have a reference sheet with info about reading output diffs

    • Your role: mark down who completed the assignment (you’ll have a spreadsheet of names), make sure they have completed it correctly -> simpler if they work together and you can grade multiple at the same time.

    • Answer questions, but try to answer groups instead of individuals - steer people towards their peers

    • Each TA will have their own color that they’re responsible for (about 20-30 students each). One TA will be a Meta TA walking around helping out as needed

    • Goal: get them started on the project, via fostering community

• Looking forward:

  • Documenting - Writing comments and multi-line comments

  • Function Development - creating more complex functions, particularly by extracting repeated code

  • Data Flow - seeing how values flow through a program

• TA Training: Problem Students I

  • “You are a Teaching assistant, not a Passing assistant”.

  • 3.1 Students who want the answer, not learning

    • Ask questions

    • Solve in a different context

    • Make them do something before going on

    • Look at them, not the computer

    • Say “no”

    • Avoid becoming an oracle

    • https://www.cs.virginia.edu/luther/ta-training/students.html#students-who-want-the-answer-not-learning

  • 3.2 Students whose question is answered in the assignment writeup

    • Ask them “Please go to the assignment writeup. Read it aloud to me.”

    • https://www.cs.virginia.edu/luther/ta-training/students.html#students-whose-question-is-answered-in-the-assignment-writeup

  • 3.3 Students who insist on doing it the wrong way

    • Neither force nor ignore

    • Give them a choice, “I can provide excellent help with a better approach, or vague help with your current approach.”

    • https://www.cs.virginia.edu/luther/ta-training/students.html#students-who-insist-on-doing-it-the-wrong-way

  • 3.5 Students who seem not to have attended class or read the textbook

    • If you have tons of time, you can teach them

    • But otherwise, redirect them to the course resources (book, slides, google)

    • If they refuse, then you can refuse to help them.

    • https://www.cs.virginia.edu/luther/ta-training/students.html#students-who-seem-not-to-have-attended-class-or-read-the-textbook

Lessons

Lesson 19- Debugging Techniques

Summary: When you encounter an error, you should attempt to debug them (using print statements, meticulously explaining your code, etc.).

Learning Objectives:

• Choose the most suitable debugging method to debug a program
• Compare and contrast different debugging techniques
• Explain how you can use automatic tracing tools to debug a program
• Explain how you can use print debugging to debug a program
• Explain how you can use code tracing to debug a program
• Explain how you can google to debug a program
• Explain how you can use rubber duck debugging

Activities:

• Lesson: Debugging
• Quiz: Debugging

Misconceptions: None listed so far

Lesson 20- Defining Functions

Summary: Function definitions have a body of code and are described by their header. Creating functions is necessary for building up programs of scale.

Learning Objectives:

• Determine if a situation could benefit from a function
• Break down a complex task into multiple function calls
• Identify the scope of variables in and outside of a function
• Define a function with a return value
• Describe the difference between parameters and arguments
• Define a function without parameters
• Define a function with parameters
• Extract a variable from a function into a parameter
• Describe the signature of a function

Activities:

• Lesson: Defining Functions
• Quiz: Defining Functions
• Programming: Defining Functions

Misconceptions:

• Students believe that any code should be encapsulated in a function, instead of code that needs to be reused or worked on in isolation.
• Students attempt to add “types” to the arguments by surrounding the parameter names with quotes, square brackets, and other literal symbols.
• Students attempt to nest function definitions into other control structures
• Students print instead of using return

Lesson 21- Unit Tests

Summary: Unit tests are used to ensure that a function is correct.

Learning Objectives:

• Explain how functions are tested for correctness.
• List advantages of using unit tests
• Intepret a failing unit test
• Describe the limitations of unit tests

Activities:

• Lesson: Unit Tests
• Quiz: Unit Tests

Misconceptions: None listed so far

Lesson 22- Return and Print

Summary: Returning from a function causes a value to be made available at the callsite. Printing from a function makes a value appear on the console.

Learning Objectives:

• Differentiate between a return statement and a print function
• Identify the output of a function that does not return anything
• Identify the output of a function that prints instead of returns
• Identify a callsite

Activities:

• Lesson: Return and Print
• Quiz: Return and Print

Misconceptions: None listed so far

Lesson 23- Scope

Summary: Variables created inside a function cannot be used outside the function, and variables created outside a function should not be used within.

Learning Objectives:

• Determine whether a variable is available within a function.
• Determine whether a variable is available outside a function.
• Determine whether a variable is aliased within a function.
• Define the difference between a global variable and a local variable.
• Explain why global variables are bad.

Activities:

• Lesson: Scope
• Quiz: Scope

Misconceptions: None listed so far

Lesson 24- Documenting

Summary: Documentation is a helpful tool for the benefit of programmers to better organize code. There are several ways to document in Python, but typically functions are documented using multi-line comments that describe the function’s inputs, outputs, and purpose.

Learning Objectives:

• Create a single-line comment
• Create a multi-line comment
• Differentiate between a single- and multi- line comment
• Explain the limitation of multi-line comments
• Explain the purpose of documentation
• Document a function’s inputs, outputs, and purpose

Activities:

• Lesson: Documenting
• Quiz: Documenting

Misconceptions: None listed so far

Lesson 25- Function Development

Summary: Functions allow us to extract commonly repeated chunks of code.

Learning Objectives:

• Use functions to solve problems
• Evaluate the name of a function
• Extract code into a function
• Define functional decomposition

Activities:

• Lesson: Function Development
• Quiz: Function Development
• Programming: Function Development

Misconceptions: None listed so far

Lesson 26- Data Flow

Summary: Data enters a function through parameters and leaves through returns. To make data available between functions, it will need to be returned.

Learning Objectives:

• Describe how data flows between two chained functions.
• Explain how values defined in one function can flow to another function.
• Describe how user input introduces new values

Activities:

• Lesson: Data Flow
• Quiz: Data Flow

Misconceptions: None listed so far