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3.7. Parity Error Checking optional

This lesson is a follow up to the error detection card trick lesson. It introduces the technical concept of parity error checking where redundant bits added to a data representation can be used to detect certain types of errors. It reinforces the enduring understanding that binary sequences are used to represent and transmit all digital data.

CSP Framework
Big Idea 2: Data (DAT)
Enduring Understanding DAT-1: The way a computer represents data internally is different from the way the data is interpreted and displayed for the user. Programs are used to translate data into a representation more easily understood by people.
Learning Objective DAT-1.A: Explain how data can be represented using bits.
Skill 3.C DAT-1.A.2 DAT-1.A.3 DAT-1.A.6 Essential Knowledge DAT-1.A.2: Computing devices represent data digitally, meaning that the lowest-level components of any value are bits. Essential Knowledge DAT-1.A.3: Bit is shorthand for binary digit and is either 0 or 1. Essential Knowledge DAT-1.A.6: Bits are grouped to represent abstractions. These abstractions include, but are not limited to, numbers, characters, and color.
Learning Objective DAT-1.B: Explain the consequences of using bits to represent data.
Skill 1.D DAT-1.B.1 Essential Knowledge DAT-1.B.1: In many programming languages, integers are represented by a fixed number of bits, which limits the range of integer values and mathematical operations on those values. This limitation can result in overflow or other errors.

Professional Development

The Student Lesson: Complete the activities for Mobile CSP Unit 3 Lesson 3.6: Parity Error Checking.

Materials

• Computer lab
• Slides
• Sets of cards and some books (for the optional extension activities)

3.7.1. Learning Activities

Estimated Length: 45 minutes

• Hook/Motivation (5 minutes): Share the cartoon and joke in the CS Unplugged activity on pg. 36:
  Q: What do you call a parrot saying "pieces of nine, pieces of nine"?
  A: A parroty error (the parrot should be saying "pieces of eight")
  (This is an old joke. It may be necessary to explain that "pieces of eight" are gold pieces.)
• Experiences and Explorations (25 minutes):
  • Explanation (5 minutes): Review the error detection card trick.Remind students that errors in data transmission and storage can occur. When errors do occur, they are detected by using parity bits.
  • Lecture (10 minutes): Use the narrative on the student version of the course. Focus on the types of parity schemes (even and odd). Students should be able to understand what a parity bit is and understand each of the parity schemes that can be used in error detection.
  • Hands on (10 minutes): Have the students work in pairs to have more practice with even and odd parity schemes. Teacher answers any questions the students might have. Use the interactive exercises in the Mobile CSP lesson.
• Rethink, Reflect and/or Revise (5 minutes): Ask the students to write a reflection in their Google portfolio that explains what they learned about even and odd parity schemes. In their reflection, students should explain how the error detection card trick involves a parity scheme.

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:

None

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.

• 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 ...

Differentiation: More Practice

Differentiation: Enrichment

Optional Extensions (50 minutes): Watch the video under the Still Curious? section as a class and practice with the sets of cards using the error correction codes. Have the students explore how check sums are used with ISBNs to determine if there was an error. (See the CS Unplugged materials for more information.)

Background Knowledge: ISBN Extension

This wiki article explains how ISBNs are constructed and what each part means.

Teaching Tips:

3.7.2. 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 the way a computer represents data internally is different from the way the data is interpreted and displayed for the user
  [EU DAT-1]
  ?

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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