I presume he changes his tests. Even if it's only because each year he thinks of something new and interesting to try, or discovered last year that one of the tests didn't work out like he'd hoped.
Ah! I was right about questioning whether the real objective was to have the strongest box! (Well, sorta.) Sounds like to me that the _real_ objective of this experiment is to produce interesting results to describe, and for the students to get some experience in how different materials respond to various damaging things.
Just build something tough. Have fun. :)
And, for extra fun, I'd suggest giving the engineering student a list of the suggestions and possibilities, and have them make all the final decisions about how to build it.
- Brooks