Lesson 3: Design Principles and User Interfaces

User Interface (UI) and User Experience (UX) design focus on how an app looks and feels. A good interface is clean, consistent, and easy to use. For example, a banking app should clearly label buttons like "Transfer" or "Pay Bill," and use colors and layouts that make sense to users. Key UI principles include contrast (readable text), alignment (organized layout), and accessibility (usable by people with disabilities). Professors may show a sample screen and ask you to identify UI problems or improvements.

Software design patterns are reusable solutions to common problems. A popular pattern in app development is MVC (Model-View-Controller): it separates data (Model), the user interface (View), and the logic (Controller). This makes large applications easier to manage. Other principles include DRY ("Don't Repeat Yourself") and KISS ("Keep It Simple, Stupid!"). In exams, you might explain a pattern or suggest a simple UI improvement (like moving a critical button to a more visible position).