Weekly Feature



2015-12-09 / Education

St. John’s students study half-life


Jason Covelli and Zach Mical work with pennies to help them understand the principle of half-life at St. John the Baptist School. Jason Covelli and Zach Mical work with pennies to help them understand the principle of half-life at St. John the Baptist School. Students experience the principle of half-life firsthand at St. John the Baptist School in Kenmore. In the study of physics, half-life is the time required for half of the atoms of a given radioactive substance to disintegrate.

The half-life of Carbon-14 is 5,730 years, meaning a 10-gram sample would take 5,730 years to disintegrate into a 5-gram sample. Half-lives can vary from several seconds to thousands of years.

Science teacher Tracy Breinlinger created a simulation activity to demonstrate this complex phenomenon to gain a deeper understanding.

“Using pennies to simulate half-life, students took 100 pennies and flipped them — resulting in heads or tails. They removed all coins that landed on heads and then flipped those remaining tails,” Breinlinger said. “Each time, they recorded the outcomes and continued to do this same procedure over again until no pennies remained. The students then graphed their results to create a model of the half-life of a penny. They were then asked to compare their simulated penny half-life graph to the half-life of Carbon-14.”

Students were also able to compare results with other students in the class to observe and draw conclusions between what occurs in a theoretical situation (each time, in theory, the number of coins should reduce in half) and compare it to what actually occurred.

As the scientific principles become more complex and abstract, Breinlinger looks to bring tangible, hands-on experiments and simulations for students to gain a firm understanding of the concept.

“Whether we’re talking about half-life of nuclear isotopes such as this situation or sea-floor spreading during Earth Science classes, many scientific concepts cannot be witnessed due to proximity, size and so on,” she said.

“Making the concepts concrete for students generally solidifies their comprehension and grasp, creating a stronger scientific background as they continue into high school and beyond,” Breinlinger added. “When students learn by doing in the lab, they are gaining a fundamental understanding and pairing it with solid skills.”

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