Outline:

1. Secret messages
   • a simple scheme
   • substitution ciphers
2. Representing strings in computers
   • ASCII and Unicode
3. Representing strings in Python
   • chr and ord
   • strings as sequences
4. Working with strings
   • basic operations
   • index function

Explore after class:

5. Exercises:
   • Exercises 1+2: strings as sequences
   • Exercise 3: indexing and slicing

Reading assignment (to be completed by the next class):

• Zelle sections 5.1-5.2 (pp. 129-136)
• Zelle sections 5.4-5.5 (pp. 139-147)
• Zelle section 5.7 (pp. 150-151)