Day 3: Binary Representation of Text

Learning Objectives

• DAT-1.C: For binary sequences in a computer, identify the data type, and interpret the values.

Essential Questions

• How is text represented in binary?
• How do different character encoding schemes support various languages and symbols?

Materials Needed

• Presentation slides on text encoding
• ASCII and Unicode reference charts
• Text encoding/decoding worksheet
• Computers with text encoding tools or websites
• Lab handout for encoding/decoding activity

Vocabulary

• ASCII
• Unicode
• UTF-8
• Character encoding
• Character set
• Code point
• Byte

Procedure (50 minutes)

Opening (8 minutes)

1. Review and Connection (3 minutes)

   • Review binary number representation from previous lesson
   • Connect to today's focus on text representation

2. Warm-up Activity (5 minutes)

   • Display several symbols on the board (letters, numbers, special characters)
   • Ask students to brainstorm: "How might a computer store these symbols?"

Main Activities (32 minutes)

3. Lecture: Text Encoding Fundamentals (12 minutes)

   • Explain the need for standardized text encoding
   • Introduce ASCII:
     • 7-bit encoding (128 characters)
     • Basic Latin alphabet, numbers, punctuation, control characters
     • Show the ASCII table and how each character maps to a number
   • Demonstrate ASCII encoding/decoding examples
   • Explain limitations of ASCII (English-centric)
   • Introduce Unicode:
     • Support for multiple languages and symbols
     • Much larger character set (over 140,000 characters)
     • Different implementation formats (UTF-8, UTF-16, etc.)
     • Backward compatibility with ASCII

4. Demo: Character Sets and Encoding (8 minutes)

   • Show how the same text looks in different encodings
   • Demonstrate encoding/decoding using online tools
   • Show examples of text in various languages and their Unicode representation
   • Explain how emojis are represented in Unicode

5. Lab: Encoding and Decoding Text (12 minutes)

   • Students work individually or in pairs
   • Part 1: Encode simple messages using ASCII (manual conversion)
   • Part 2: Decode ASCII values to reveal hidden messages
   • Part 3: Explore Unicode characters and their code points using online tools
   • Part 4: Create a message using both ASCII and non-ASCII Unicode characters

Closing (10 minutes)

6. Discussion and Reflection (5 minutes)

   • How has text encoding evolved to become more inclusive?
   • Why is standardization important for data representation?
   • What challenges might arise with text encoding in global communications?

7. Lab Report and Preview (5 minutes)

   • Students complete a brief lab report summarizing their encoding/decoding activities
   • Preview that next class will focus on image and sound representation

Assessment

• Formative: Participation in encoding/decoding activities
• Lab Report: Accuracy of encoding/decoding and quality of reflections

Differentiation

For Advanced Students

• Explore UTF-8 variable-length encoding and its efficiency
• Create messages that combine multiple languages and special characters
• Research how programming languages handle different text encodings

For Struggling Students

• Focus on ASCII encoding before introducing Unicode
• Provide reference sheets for encoding/decoding
• Use visual aids to illustrate the encoding process

Homework/Extension

• Complete any unfinished lab activities
• Create a "secret message" encoded in ASCII for a classmate to decode
• Research how a language of your choice is represented in Unicode

Teacher Notes

• Emphasize the historical context of ASCII and why Unicode was needed
• Make connections to students' experiences with different languages and emojis
• Be prepared to address questions about specific character encodings
• Point out that text encoding is fundamental to file formats, web pages, and programming