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3.5. Paint Pot Refactoring and Documentation

This lesson modifies the app enhanced in the 'Paint Pot Projects', not to change any functionality, but to improve the code, a process called refactoring. In this case we will introduce the concept of a programmer-defined procedure that will help reduce the complexity of our code and make it easier to read and maintain. A procedure is a named grouping of instructions that can be used where needed in a program by invoking its name. This is known as 'calling a procedure.' This lesson reinforces the enduring understanding that procedures are useful abstractions that are used by programmers to structure and simplify programs (procedural abstraction). We will also add comments as a way of documenting the purpose of the procedure.

CSP Framework
Big Idea 1: Creative Development (CRD)
Enduring Understanding CRD-2: Developers create and innovate using an iterative design process that is user-focused, that incorporates implementation/feedback cycles, and that leaves ample room for experimentation and risk-taking.
Learning Objective CRD-2.G: Describe the purpose of a code segment or program by writing documentation.
Skill 4.A CRD-2.G.1 CRD-2.G.2 CRD-2.G.3 CRD-2.G.4 CRD-2.G.5 Essential Knowledge CRD-2.G.1: Program documentation is a written description of the function of a code segment, event, procedure, or program and how it was developed. Essential Knowledge CRD-2.G.2: Comments are a form of program documentation written into the program to be read by people and do not affect how a program runs. Essential Knowledge CRD-2.G.3: Programmers should document a program throughout its development. Essential Knowledge CRD-2.G.4: Program documentation helps in developing and maintaining correct programs when working individually or in collaborative programming environments. Essential Knowledge CRD-2.G.5: Not all programming environments support comments, so other methods of documentation may be required.
Learning Objective CRD-2.H: Acknowledge code segments used from other sources.
Skill 1.C CRD-2.H.1 CRD-2.H.2 Essential Knowledge CRD-2.H.1: It is important to acknowledge any code segments that were developed collaboratively or by another source. Essential Knowledge CRD-2.H.2: Acknowledgement of code segment(s) written by someone else and used in a program can be in the program documentation. The acknowledgement should include the origin or original author's name.
Learning Objective CRD-2.I.a: For errors in an algorithm or program: a. Identify the error. Learning Objective CRD-2.I.b: For errors in an algorithm or program: b. Correct the error.
Skill 4.C CRD-2.I.5 Essential Knowledge CRD-2.I.5: The following are effective ways to find and correct errors: test cases, hand tracing, visualizations, debuggers, and adding extra output statement(s).
Big Idea 3: Algorithms and Programming (AAP)
Enduring Understanding AAP-3: Programmers break down problems into smaller and more manageable pieces. By creating procedures and leveraging parameters, programmers generalize processes that can be reused. Procedures allow programmers to draw upon existing code that has already been tested, allowing them to write programs more quickly and with more confidence.
Learning Objective AAP-3.B: Explain how the use of procedural abstraction manages complexity in a program.
Skill 3.C AAP-3.B.1 AAP-3.B.2 AAP-3.B.3 AAP-3.B.4 AAP-3.B.6 AAP-3.B.7 Essential Knowledge AAP-3.B.1: One common type of abstraction is procedural abstraction, which provides a name for a process and allows a procedure to be used only knowing what it does, not how it does it. Essential Knowledge AAP-3.B.2: Procedural abstraction allows a solution to a large problem to be based on the solution of smaller subproblems. This is accomplished by creating procedures to solve each of the subproblems. Essential Knowledge AAP-3.B.3: The subdivision of a computer program into separate subprograms is called modularity. Essential Knowledge AAP-3.B.4: A procedural abstraction may extract shared features to generalize functionality instead of duplicating code. This allows for program code reuse, which helps manage complexity. Essential Knowledge AAP-3.B.6: Using procedural abstraction helps improve code readability. Essential Knowledge AAP-3.B.7: Using procedural abstraction in a program allows programmers to change the internals of the procedure (to make it faster, more efficient, use less storage, etc.) without needing to notify users of the change as long as what the procedure does is preserved.
Learning Objective AAP-3.C: Develop procedural abstractions to manage complexity in a program by writing procedures.
Skill 3.B AAP-3.C.1 Essential Knowledge AAP-3.C.1: The exam reference sheet provides PROCEDURE procName(parameter1, parameter2, …){ } which is used to define a procedure that takes zero or more arguments. The procedure contains block of statements.

Professional Development

The Student Lesson: Complete the activities for Mobile CSP Unit 3 Lesson 3.5: Paint Pot Refactoring and Documentation.

Materials

• Presentation system (LCD projector/Interactive whiteboard)
• Access to computer, laptop, or Chromebook (install the Companion app on Chromebooks)
• Access to mobile device with the Companion app installed or access to the emulator installed on the computer or laptop. 
• Paint Pot Refactoring Text Version or Videos
• Wikipedia article on refactoring

3.5.1. Learning Activities

Estimated Length: 45 minutes

• Hook/Motivation (5 Minutes): Here are some suggestions.
  • Show the students the lyrics of a children's song where there is a chorus like This Old Man and have them point out any lines that are repeated. These can be pulled out into a procedure called chorus and called whenever needed. This is procedural abstraction.
  • Show the students the code from a finished Paint Pot app or the template for this app. Ask them to find the duplicated code, i.e. the same blocks of code that are used in more than one event. They should identify the blocks to update the dot size label. Explain that you will learn how to create procedures, which give a name to a block of code that can then be reused in the program. You will also be adding comments to the procedure to document what it does for yourself and other programmers.
• Experiences and Explorations (20 minutes): Instructors can lead students through the tutorial, can show the video (4:32), or can allow students to watch it on their own. Students can work in pairs to either update their existing app from the Paint Pot Projects lesson, or they can use the template provided in the lesson.
• Rethink, Reflect and/or Revise (20 minutes):
  • Students should work on completing the self-check exercises. If time, review them as a class to ensure students are writing procedures correctly.
  • In their portfolios, have the students answer the portfolio reflection questions found in the Mobile CSP lesson. Now that they've refactored their code, ask them how many blocks would need to change in the code if they wanted to use a slider or another UI component to display the dot size to the user? Do they think it is easier or harder with the procedure? Can students think of where they might add comments or procedures in other apps they have created?

AP Classroom

The College Board's AP Classroom provides a question bank and Topic Questions. You may create a formative assessment quiz in AP Classroom, assign the quiz (a set of questions), and then review the results in class to identify and address any student misunderstandings.The following are suggested topic questions that you could assign once students have completed this lesson.

Suggested Topic Questions:

• Topic 1.4 Identifying and Correcting Errors 
  

Assessment Opportunities and Solutions

Solutions Note: Solutions are only available to verified educators who have joined the Teaching Mobile CSP Google group/forum in Unit 1.

• Paint Pot with Procedures .aia file
• Quizly Solutions
• Portfolio Reflection Questions Solutions

Assessment Opportunities

You can examine students’ work on the interactive exercise and their reflection portfolio entries to assess their progress on the following learning objectives. If students are able to do what is listed there, they are ready to move on to the next lesson.

• Interactive Exercises:
• Portfolio Reflections:
  LO X.X.X - Students should be able to ...
• In the Paint Pot App, look for:
  - Correct definition of a procedure
  - Correct calling of a procedure
  - Appropriate use of comments to document the procedure

Differentiation: More Practice

Students can watch this 1-minute video on defining a procedure or read more about procedures in the AI Documentation.

Differentiation: Enrichment

Students can review previous apps to see if they should add comments or procedures anywhere else.

3.5.2. Professional Development Reflection

Discuss the following questions with other teachers in your professional development program.

• How does this lesson help students toward the enduring understanding that programming is facilitated by appropriate abstractions, such as procedures?

I am confident I can teach this lesson to my students.
• 1. Strongly Agree
• 2. Agree
• 3. Neutral
• 4. Disagree
• 5. Strongly Disagree

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