Untitled Document

Students learn principles of bridge design
from toothpicks, glue and ITD volunteers

All you get is 250 toothpicks and 1.25 ounces of Elmer’s glue to construct a six-inch bridge. Do it right and it might hold 100 pounds.

The first goal however, is hope that it will hold the three-pound test bucket.

From the start, just holding the bucket drew a gasp from a handful of fourth grade students at Morningside elementary in Twin Falls on May 28. Watching the first bridge hold 24 pounds drew a big cheer.

The class was graded on the construction and design of the bridge, but breaking them was just for fun. Hanging a bucket to be filled with sand one cup at a time tested the strength of the structures.

“The kids just love this,” said teacher Carmela Rush.

Recruited to help teach the kids about bridges and how to design them was Rush’s father, ITD staff engineer Steve Tonks.

Tonks helped conduct the contest in two schools this spring – Hagerman Middle school and Morningside Elementary. The contest offered more than just fun for the students; it also carried a math lesson.

“Knowing how the geometry of a structure can help carry a larger load is a small lesson but means a lot for this age group,” Tonks said.

A former bridge designer for the Washington Department of Transportation, Tonks used his knowledge to help design toothpick bridges for his children. One held over 100 pounds before it started cracking. Another nearly 70 pounds.

After it cleared 100 pounds my son asked that we save the bridge,” Tonks said.

See the District 4 newsletter, Interchange