Raspberry Pi Programming - typical electric components

Raspberry Pi provides a great platform to learn programming and gain knowledge of basic electric components.

At this moment I am considering that the most basic projects for a newbie with no educational background in electrical or electronic engineering would cover;

1. Basic of electric circuits and personal safety
2. Use of battery, LED and resistors
3. Buzzer and sensors

The Raspberry Pi would then be connected to turn on/off and detect state of the component. Basics of Python programming would be needed, see my previous post. This is going to be fun, but expect some parts to get fried along the way even with only 3volts.

Next couple of days will be used to sort out which components for upcoming basic projects.

Which components should I use?