Ask HN: Career Fair Presentation about Software Engineering

On Friday I will give a presentation about Software Engineering at a career fair at an international school in Vienna. The attending students will be between 12 and 18 years old and I will have 30 minutes time (including Q&A).

I'm planning to show some of my projects (mobile and web apps) but also give a broad view of what they could work on after studying computer science.

What would you talk about or make sure to mention?