Sometimes a full size Arduino is a bit on an overkill if for example you just want to blink one LED.

Fortunately there is a smaller and cheaper version of microcontroller used by Arduino called the Attiny. We have included one in the workshop kit, it's a small 8 pin chip that is stuck into a foam pad.

You can program this chip using your Arduino. Instructions are provided here: http://highlowtech.org/?p=1695 you need to follow the sections relevant to using Arduino (as ISP) to an ATtiny.

Easier(1) Flash an LED on/off once a second using just you Attiny.Intermediate(2) Adjust the speed of flashing by using a potentiometer (ask a helper for one if you don't have one from a previous workshop kit.)