[artdutra04]

Being the kind of person who likes to work their their hands (as opposed to doing administrative paperwork), I'd say keep the Vex robots, and if you do get some NXT kits, use them as well. But before I could offer more substantial advice, I'd like to know if this 'homeroom' idea is for the entire year?

25-30 minutes of work per day may be frustrating, but 25 minutes on two of five days per week ends up being 30 hours for the entire school year. For me personally, this would be enough time to build two complete (and complex) Vex robots, with still more than enough time left over to compete.

I'd say your best bet (with Vex or NXT) would be to set up extremely simple challenges. Don't even make them a game, just a challenge. Use electrical tape on the white linoneum floors to make a crazy line-following course. (A 'figure eight' makes it even better!) Have them autonomously try to make a robot that can navigate the room without hitting anything using ultrasonic sensors.

Keep the projects (on the robot construction and programming end) simple, but enough to introduce students into the world of robotics. A Vex Squarebot (with the addition of a multitude of sensors) is perfect for this. If they need to create arms, manipulators, etc. then it's probably too complex for your time limits.