Although there is a bit of a conflict with build and competition dates, I'd like to point those who are not familiar with the West Point Bridge Design contest to the website:
http://bridgecontest.usma.edu/
I've had students use the software and take part in the contest for over a decade now. I've even competed myself, in the "open" category and managed to get in the top ten scores... at least for a while.
The help files are great at explaining a lot of civil/mech/materials terms, and while you don't have to do a lot of math to build your bridge, you certainly need to understand truss design to do well.
Students who are American citizens are even eligible to win scholarships.
Teachers... if you've got a classroom with computer access and you need to keep the kids busy doing something productive for a few days while you fill out travel permission forms, contact sponsors, or do the last minute rush to bag or box your robot... I've used this with grades 8 - 12 and it keeps all of them interested and productive as they each try to best the other. Its also a great lesson plan to leave for your sub when you head off to a competition.
Enjoy,
Jason
P.S. It's free! (Thank you, United States Military Academy)