The New Solder : Time II™ Watch Kit.
The Solder : Time II is the the latest upgrade of the popular Solder : Time Watch Kit. This new version is even more hackable than the original. The onboard microcontroller in this model is the very popular ATmega328P used in many of the current versions of Arduino. In fact, you can reprogram your watch using the same IDE software that you use for a regular Arduino.
The Solder : Time II is different from the original Solder Time in many ways. The display has been upgraded to a set of four 5×7 LED matrix modules. This gives you control of a 7×20 matrix for a total of 140 LEDs!
The new LED matrix allows for an amazing amount of information to be displayed, aside from the current time: the date, month, words, scrolling messages, graphics, and special characters. The possibilities are endless.
The ST2 comes with a piezo buzzer for the alarm function, but you can also use it to add sounds to you custom programming and games.
Classroom 10-pack kits are $531 direct from Spikenzielabs here. They are also sold individually online at various sites for $59.95 each.