2. Figure 1.1
The life cycle of software as a water wheel that can rotate from one phase to any of phase

3. Figure 1.2
The details of the sorting algorithm are hidden from other parts of the solution.

4. Figure 1.3
A digital clock

5. Three Principles of Object-Oriented Programming
Encapsulation: Objects combine data and operations.
Inheritance: Classes can inherit properties from other classes.
Polymorphism: Objects can determine appropriate operations at execution time.

6. Figure 1.4
A structure chart showing the hierarchy of modules

7. Key Issues in Programming
Modularity
Modifiability
Ease of use
Fail-safe programming
Style
Debugging

8. Essential Features of Program Documentation
Statement of purpose
Author and date
Description of the program’s input and output
Description of how to use the program
Assumptions such as the type of data expected
Statement of exceptions
Brief description of the major classes
Comments in each class
comments in each method
Comments in the body of each method