Middle school students learn about osmosis and how cell membranes work by dissolving the shells off of eggs

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Woodland Middle School students in Jennie Zarosinski's Life Science classes dissolved the shells off of eggs using vinegar to study shell-less eggs and learn how cell membranes work.

Jennie Zarosinski, a science teacher at Woodland Middle School, uses hands-on experiments so students can experience what they're learning.
Jennie Zarosinski, a science teacher at Woodland Middle School, uses hands-on experiments so students can experience what they're learning. 

Zarosinski developed an experiment for students to see how cell membranes work in the real world. Students soak eggs in a vinegar solution for several days to dissolve the shells off of the eggs. Each day, students use lengths of string to measure the circumference of their intact eggs and weigh them to determine their mass, recording the results and observing the day-to-day changes. Students also identify other characteristics of their eggs such as color, texture, and mass. Using those measurements and observations, students develop hypotheses about what they thought would happen next.

Students scoop their egg out of the vinegar solution so they can conduct their daily measurements and observations.
Students scoop their egg out of the vinegar solution so they can conduct their daily measurements and observations.

After a few days, students use the data they collect to determine whether they have enough information to prove or disprove their hypotheses, and discuss both their scientific questions and hypotheses with each other to help clarify their results. In this case, the eggs increased in size each day as the vinegar solution seeped into the egg through the process of osmosis.

Students learned about osmosis during the cell membrane classroom unit accompanying the experiment, making the hands-on experience an incredibly powerful teaching tool. "Cell membranes are semi-permeable which means they allow liquid to pass through them from a process called osmosis," explained Zarosinski. "By conducting this experiment, students can see how osmosis works first-hand."

Students learn about osmosis by observing how the egg grows in size as the vinegar solution permeates its membrane.
Students learn about osmosis by observing how the egg grows in size as the vinegar solution permeates its membrane.

For Zarosinski, coming up with new experiments to help provide hands-on experiences for students to learn material is a big part of teaching. This is the first time she's used the cell membrane experiment with her classes. "I'm always looking for more hands-on experiments so students can learn by performing practical work," she said. "I'm very fortunate to have a lab classroom like this one where students can use chemicals and conduct exciting experiments."

Students are excited to use experiments to learn. "Science class is a lot of fun because of the experiments and hands-on work," said Elana Koutny, a seventh grader. "Mrs. Z does a great job explaining the material, too!" Kayla Miller, a seventh-grade classmate, agreed with Koutny, "It's fun to see what happens throughout the course of an experiment and discovering new things."

Before becoming a teacher, Zarosinski worked as a microbiologist for nearly 30 years. About three years ago, she decided to become a teacher so she could share what she learned as a scientist. "I wanted to teach everything I learned about the world to kids," she explained. "I love the 'ah-ha' moments when students observe exciting things; to me, that's what science is and that's what motivates me – I want to see students discovering new concepts and connecting with those concepts through their own actions."

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