The Robotics Club was an after-school extracurricular activity.  We used the Hummingbird Kit found here:  hummingbirdkit.com

This kit provides a variety of sensors, lights, motors, and servos.  The visual programming interface is easy to use and very quick to learn and produce working models.  The “robots” are tethered to the computer because the software on the computer drives the interface board.  The motors also require more power than USB can provide so the board requires a power supply as well.

Videos of the final robot following a white line on the floor are found at:

http://www.youtube.com/user/MisterLaskowski

The logic is very simply:

• Loop
•    if on tape
•       move forward
•    else
•       stop
•       back right 1 unit
•    if on tape
•       move forward
•    else
•       back left 2 units (to make up for a possible right error)