For Northland high school students, it's a test of the trusses
Sierra Offersen was quick to answer when asked how long it took her to build her elegant toothpick bridge.
"Thirty hours," the ninth-grader from Hermantown said.
It was easy to calculate because that's how many episodes of the television show "Supernatural" she watched at home while gluing hundreds of toothpicks into the form of her bridge.
Offersen was one of many high school students from the region who took part in the 21st annual toothpick bridge building contest Wednesday in the engineering department at the University of Minnesota Duluth.
Offersen was an early trophy winner in the packed lab in the civil engineering building. Her bridge was deemed the "most aesthetically pleasing" before the real business of the day took place -- testing the strength of more than 120 bridges.
No matter how many times bridges snapped under the weight of a bucket of sand, students who were hovering flinched.
"No more crack," Duluth East ninth-grader Ben Weaver yelled when someone told him they heard his bridge failing.
The scolding worked, and Weaver was able to add several more scoops of sand to the bucket before his bar-joist creation broke in two under the weight of just more than 100 pounds. It was a good number, but other bridges were taking on more.
Todd Bergstedt, a science teacher at Hermantown, said the contest is a fun way to teach physics. His school is late to the party, competing in only its second contest. He lets the students mostly work on their own at home.
"You have parents. You have the Internet," he said of what he tells his ninth-graders. "We have fun with it."
Toothpicks are provided and there is a bridge weight limit to keep the playing field level.
The Duluth chapter of the American Society of Civil Engineers hosts the event. Member John Hinzmann said the contest is an ideal way to introduce teenagers to engineering. He joked that "hopefully all" of the students that have gone through the contest end up in engineering fields.
"This is the hook," said Cromwell math teacher Pete Koenig. "It all comes together. It becomes real and they might say 'This is for me.' "
Koenig uses the contest as part of his geometry curriculum. He said it's important that students from his rural school show up and find a lot of people "doing big things."
East and Bayfield are perennial powers at the contest.
Bayfield has the all-time strength record of 268 pounds. The Wisconsin school had the top two strength spots, with bridges holding up to 168 and 139 pounds. Bayfield also had the most economical bridge, which is judged by a ratio of how much the bridge weighs with how much weight it holds.
More than 400 East students built bridges. Then there was the "break-off," said science teacher Pete Tideman. A bridge must pass a test of holding 50 pounds of weight. Those that passed were sent to UMD.
Weaver's father is an engineer who offered moral support for his son.
"He said it would hold a lot," Weaver said while texting news of his 100-pound feat to his dad. "It worked."
Typical for students with three-plus years of high school ahead, Weaver and Offersen are keeping their options open as far as interests into adulthood.
Offersen said she'd like to be an eye doctor, or work in a neonatal unit or become an author.
But first, she's taking career goals one step at a time. She was proud to hold the trophy for the best-looking bridge. She used a sanding tool to smooth out the glue drops and applied a thin layer of glue to give some sheen to the exterior.
"The goal here is get an 'A,' " she said as she held her bridge, waiting for it to be crushed under a weight she hoped she could be proud of.