I made one in physics in 12th grade.
Is this where you try to get it to hold a bunch of weight?
I got an A on mine---Want to say it held somewhere between 150 and 250 pounds, but I just don't remember.
Is it for a badge???
Does it have to look like a bridge. Mine looked nothing like a bridge--but I basically used the sticks to reinforce one another along the lines of the triangle bit.
If for a badge--I would suspect the idea was the same as when I did it--using science and math to discern the best way to build the bridge on his own.