Eggcelent Education

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Interactions - SPS Chapters in Action

Eggcelent Education

Trebuchet Teams Face Off with Physics 


Jason Stock at Idaho State University

An elementary school student triggers his homemade trebuchet. Photo by Jason Stock.

“One meter!”

As the judges call out the distance, murmurs can be heard from all directions. Those murmurs are quickly drowned out by the giddy screaming of two 5th-grade girls. The two girls are competing in the Elementary School Egg Launch, put on by Idaho State University’s SPS chapter. They have just made the winning shot in the accuracy challenge with their first-ever trebuchet. An egg launched nearly 50 meters was only 1 meter off its target.

The father of one of the girls stands behind them, looking very proud of his daughter. Other parents and teachers drink hot chocolate or cider as they try to stay warm on the cold December day. None of the children seem to notice the chill. They are all very absorbed in their machines, making fine adjustments and hoping to hit their targets or maximize their distances.

The trebuchet was once a tool for destruction. It revolutionized modern warfare. The British Warwolf, one of history’s most famous trebuchets, seemed unstoppable when it was built in the 13th century, a mighty machine that could tear down any fortress.

But on this day the trebuchet became a tool for education, an optimal example of classical mechanics. Each machine in the competition was an elegant system that took the potential energy of a suspended mass and used a mechanical advantage to propel a smaller mass remarkable distances.

Competitors watch the egg they launched fly through the air. Photo by Jason Stock.Students from the ISU SPS chapter spent much of last year volunteering their time to help run classes in trebuchet building and to coach teams for this competition. The elementary school students learned basic physics concepts such as conservation of energy and the effects of lever arms on torque. The students were also taught how to use reference materials to develop their own designs and build the machines that finally came together for the egg launch.

Overall, the day was a fantastic success. Five teams from four schools showed up, about 30 people altogether. At the end of the day, it was clear the egg launch achieved its goal.

The event made an impact on the participants, and, even more importantly, on the Pocatello, ID, community as a whole. Teachers and parents talked about making the competition a regular event. At the end of the day, a seed had been planted in support of science education. A seed . . . or maybe an egg. //

Further Information

Watch ISU’s SPS chapter oxidize coffee creamer in a public demo at

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Interactions - SPS Chapters in Action