One of the first things I wanted to learn in electronics as a kid was how to blink a light.
There are several ways of doing this, but this circuit is probably the easiest way to do it when it comes to the number of components. You only need three components for the blinking part. Then the resistor and LED to be blinked of course.
These lessons are originally from a free email course I made for my blog, but it's adapted and expanded to fit the course format here on Ohmify.
The idea behind the course is to teach a practical circuit to a complete beginner.