This challenge, along with the ARTbot and Sumobot challenges were so successful in that the competition aspect really propelled student teams to explore other design solutions on their own, in order to beat the other guy. I am quickly realizing that the sooner I get to the competitions, the more engaged my students become and the deeper the learning that occurs. I simply need to weave in mini-clinics on gear ratio, algorithms, linkages, mechanisms, etc. as we go. I try to avoid a full-on lecture whenever possible.
Maybe most importantly, I have found that modeling the build for a particular challenge is incredibly important. Not only do students get to see me try and fail (as part of the iterative design process), it also builds rapport with students and allows them to "reverse engineer" and improve in their own way some of the solutions I explore. And of course, they love it when they beat me, which instills an enormous sense of pride in them (and me, too).
The act of teaching Robotics itself is subject to the design process. One of these days, I'll get it right. :)
Here's a quick vid I shot about my own Robo-Dragster. Usually, I use Sony Vegas to create videos, but lately I've been using WeVideo lately to produce my videos. It's web-based and there's a free version, if you're interested. I paid $12.00 (I think) to get a little more monthly space and the ability to export 720 without a watermark. So far, I like WeVideo. Its interface is easy to navigate, I like the templated graphics and the bank of decent license-free music beds. It also seamlessly exports to Youtube, Vimeo, etc.