# 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.

### 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.

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: 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.

## 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