Did anyone else do this as a kid?
I sure did - Science Olympiad! You had to span ~300mm and hold up to a bucket of sand, or about 65-70#. Your score was a mass ratio of load/bridge.
Back in 1989, besides being a star mathalite, I dabbled in the civil engineering.
20.8 grams, maxed the bucket for maybe 1500ish points. Took second in my region.
Only second among fellow ninth graders in our small town but still - weighed less than an ounce and held over 69 pounds.
I vaguely recall that in the early '90s, besides the super awesome concrete canoe, our uni's civil engineering department had a big steel bridge comp. I think it was a thing for the big civil engineering national body (like ASME but a little less dynamic). They were far larger than middle-schoolers, I think they were ~15' spans with kilopound loads. Failures were far louder than my puny balsa bridge...