So what is Arduino?

From Wikipedia:

Arduino is a single-board microcontroller, intended to make the application of interactive objects or environments more accessible.^[1] The hardware consists of an open-source hardware board designed around an 8-bit Atmel AVRmicrocontroller, or a 32-bit Atmel ARM. Current models feature a USB interface, 6 analog input pins, as well as 14 digital I/O pins which allows the user to attach various extension boards.

Introduced in 2005, the Arduino platform was designed to provide an inexpensive and easy way for hobbyists, students and professionals to create devices that interact with their environment using sensors and actuators. Common examples for beginner hobbyists include simple robots, thermostats and motion detectors. It comes with a simple integrated development environment (IDE) that runs on regular personal computers and allows users to write programs for Arduino using C or C++.

The current prices of Arduino boards run around €20, or $27 and those of related "clones" as low as $9. Arduino boards can be purchased pre-assembled or as do-it-yourself kits. Hardware design information is available for those who would like to assemble an Arduino by hand. It was estimated in mid-2011 that over 300,000 official Arduinos had been commercially produced, and in 2013 that 700,000 official boards were in users' hands.

Don't run away if the description there scares you, as it would me until recently.  Full disclosure:  I had hardly touched a computer until I was 27, and didn't know rip about chips, programming, and the like.  If I can get into this stuff, you can.  Arduino was suggested to my by a friend's son as the hot new thing for people who want to really DO stuff with technology but were total amateurs.   You can find Arduino at Radio Shack for pretty cheap, and a whole host of add-ons through many suppliers.  I tend to use Sparkfun, which is very oriented towards teachers and has designed a host of classroom-friendly stuff. 

Arduino is an open source platform with tons of free tutorials, sample programs, how to's, and one of the fastest online forum response turnovers you'll ever see.  Check out their site.