Day 4: Strings and String Operations

Learning Objectives

• AAP-1.C: Represent a list or string using a variable.
• AAP-1.D: For data abstraction: Develop data abstraction using lists to store multiple elements.
• AAP-2.D: Evaluate expressions that manipulate strings.

Essential Questions

• How are strings represented and manipulated in programs?
• How can we use string operations to process text data?

Materials Needed

• Presentation slides on strings and string operations
• Programming environment
• String manipulation worksheet
• Sample text processing program
• Exit ticket templates

Vocabulary

• String
• Character
• Concatenation
• Substring
• Index
• Length
• String operation
• Text processing

Procedure (50 minutes)

Opening (8 minutes)

1. Review and Connection (3 minutes)

   • Review expressions and operators from previous lesson
   • Connect to today's focus on strings and text manipulation

2. Warm-up Activity (5 minutes)

   • Display several string examples and ask students to identify what operations might be useful
   • Discuss real-world scenarios where text processing is important

Main Activities (32 minutes)

3. Lecture: String Representation and Operations (12 minutes)

   • Define strings as ordered sequences of characters
   • Explain how strings are represented in memory
   • Introduce string operations:
     • Concatenation (joining strings)
     • Substring extraction
     • Length determination
     • Accessing individual characters by index
   • Demonstrate how each operation works with examples
   • Explain how strings can be stored in variables
   • Show how strings can be combined with other data types
   • Discuss common string processing tasks (searching, replacing, etc.)

4. Demo: String Concatenation, Substring, Length (8 minutes)

   • Walk through examples of string operations step-by-step
   • Show how to combine multiple operations
   • Demonstrate common patterns for text processing
   • Illustrate how strings are immutable in many languages
   • Show examples of string formatting and presentation

5. Hands-on: Manipulating Strings in Code (12 minutes)

   • Students work in the programming environment
   • Guide students through creating and manipulating strings
   • Have students write code to perform various string operations:
     • Joining first and last names
     • Extracting parts of addresses or phone numbers
     • Converting text formats
     • Building formatted output
   • Include exercises that combine string operations with other concepts

Closing (10 minutes)

6. Activity: Creating a Simple Text Processor (5 minutes)

   • Students work on a mini-project to create a simple text processor
   • The program should take input text and perform operations like:
     • Counting characters or words
     • Converting case (uppercase/lowercase)
     • Finding and replacing text
     • Formatting text in a specific way
   • Share and discuss different approaches

7. Exit Ticket and Preview (5 minutes)

   • Students complete a program that processes and manipulates strings
   • Preview that next class will focus on algorithm design and testing

Assessment

• Formative: Participation in hands-on activities and string manipulation exercises
• Exit Ticket: Functionality and correctness of string processing program

Differentiation

For Advanced Students

• Provide more complex text processing challenges
• Introduce additional string operations (regular expressions, etc.)
• Challenge them to create a more sophisticated text processor

For Struggling Students

• Focus on basic string operations before combining them
• Provide code templates for string manipulation
• Use visual aids to illustrate string operations

Homework/Extension

• Complete a worksheet with string manipulation exercises
• Create a program that processes a specific type of text (names, addresses, etc.)
• Research how different programming languages handle string operations

Teacher Notes

• Emphasize that strings are sequences and can be processed character by character
• Watch for confusion about string indexing (some languages start at 0, others at 1)
• Make connections to real-world applications of text processing
• Consider using physical cards with letters to demonstrate string operations
• Remind students that string processing is a common task in many programs