By Katy Macek
The Chippewa Herald
CHIPPEWA FALLS (AP) — Seventh-grader Jacoby Yliniemi dropped a bowl of sand into the bucket being held up by his group’s toothpick bridge, bit his lip and then relaxed.
The bridge was safe; at least for a second.
Another moment passed, a toothpick could be heard snapping just before his class gasped and the bridge, which had been held up between two tables, fell into the bucket below.
“Well, it was stronger than I thought it would be,” Jacoby told the Chippewa Herald.
Jacoby and his team members, Evelyn Kelly and Aiden Johnson, are part of Chelsey Zoromski’s seventh-grade science class at Chippewa Falls Middle School.
The groups of three to four students have spent the last two weeks researching, planning and building their own bridges. Last week it was time to put them to the test.
This is the fourth year the science department has created toothpick bridges, Zoromski said. The exercise as part of the seventh-grade’s engineering standards curriculum.
“We really wanted to incorporate projects that were hands on and worked through the engineering process,” Zoromski said.
The goal of the project is to design a bridge that would be most practical for the city of Chippewa Falls to build.
Before building, the students researched different types of bridges and analyzed why certain ones collapsed, using real-life examples such as the I-35W bridge collapse in 2007 in Minneapolis.
The groups had to choose the design of their bridge and then plan how to build. Because toothpicks are not bendable and create triangles easily, she said most groups chose to create a truss bridge, which is formed using triangular patterns.
They were also required to follow certain instructions relating to the span of the bridge, the deck, width, height and boat clearance. Each group was given a $1 million budget to spend on materials (toothpicks, glue, cost of land, use of wire cutters, wax paper, tape and graph paper) and the $100,000 consulting fee.
“Everything they used cost money, and if they lost things, they paid a fine to get it back,” Zoromski said. “It’ll be useful for them to have that practical experience of going through an engineering project, but we also tried to relate it to real life.”
So how much weight can a toothpick bridge hold?
The science department’s record of 28 pounds was set in 2015, but Zoromski said this year’s winning bridge was created by Makenzie Gale, Mason Bruhn and Balie Schultz. It held 56.8 pounds, more than doubling the 2015 record.
The bridge Jacoby, Evelyn and Aiden built held 34.39 pounds, which held the most weight in Zoromski’s fourth-hour class.