On the traces of the isotopes from grass to milk – a new workshop for schools

The call for workshops came more than a year ago: To mark the 150th anniversary of Agricultural Sciences at ETH, students from high schools were to be invited to ETH for an “Open Week Education” to get a taste of research in agricultural sciences. I found the idea very appealing of developing a workshop for high school students and giving them an understanding of our group's research. But how to proceed when our research takes place in remote, decentralized fields and mountain forests?

Our on-site labs are not very spacious, and they are primarily used for preparing field samples for the IsoLab, which is what our Stable Isotope Laboratory is called, with 'Burns' and 'Convertino'. The latter are our two isotope ratio mass spectrometers (yes, a former lab manager was a fan of the band Calexico). More than five thousand samples are burned here every year and broken down into their isotopic compositions. Isotopes are atoms with the same number of protons, that is, from the same chemical element, but which can have a different number of neutrons in the nucleus and thus a different atomic weight.

No field around the corner? Then let's focus on the method

So, how can we host a school class and do something cool with the kids in our lab? That's when I got the idea to focus on the IsoLab itself and the method of mass spectrometry of stable isotopes. It turned out not to be an easy task, since the topic of stable isotopes is very complex for nonprofessionals (I speak from personal experience). At the same time, I was fascinated by the detective aspect of the method used to deduce production differences along the food chain due to distinctions in the isotopic composition of products. It can be used to find out, for example, whether an asparagus was grown in Switzerland or Spain, or whether the hay milk cheese really comes from milk from cows that have spent the summer on pastures. Different forms of nutrition (e.g., vegan vs. vegetarian) can also be detected in human hair.

The dilemma between scientific precision and didactic reduction

So, I immersed myself in the subject and reemerged several months later with plenty of new experiences: As the author of the handout, traveling on “unfamiliar” territory, I practiced the dilemma of “complex” didactic reduction: The isotope specialist editor demands precision, the specialist of didactics simplification. In addition to my roles as a storybook writer and a director for a video documentation of the process of isotope measurement from the plant in the field to the finished measurement curve, I also acted as troubleshooter: the latter of course didn't stop before the day of shooting. Just when we started filming in the corridor and in the laboratory (during a public holiday), a craftsman with a drill and a folding ladder stood in front of the door. He had to come back another time...

Ready for the workshop (Picture: ValentinKlaus)

Allocating the students into groups (Picture: Valentin Klaus)

From theory to practice: does the workshop work?

Everything was finally ready, and the “Open Week Education” was also set after it had been postponed twice due to the pandemic. Therefore, I was particularly pleased that two classes from a local high school had booked the workshop. However, they wanted to come together, the next - especially logistical - challenge. Because of the small laboratories, the two classes were divided into six groups, which then visited our research rooms during a guided tour and were able to produce milk powder in the laboratory in rotation. The students had to find out from unknown milk samples how the milk had been produced (organically vs. conventionally). To do this, they had to consider what influence the composition of the feed and the fertilization of the feed could have on the carbon and nitrogen isotope composition.

Fortunately, everything went well, and the workshop was well received by the students and the teachers. The pupils were able to get a taste of ETH for the first time, and they were also introduced to the studies of Agricultural Sciences at D-USYS. Now we are looking forward to many visits from high school classes. The next workshop is already booked.

ABOUT THE AUTHOR

Sabina Keller is a lecturer and outreach specialist in the group of Grassland Sciences. She has developed workshops and events for different target groups in cooperation with several internal and external actors (e.g., Plant Science Center, GLOBE Swiss, Kangaroo goes Science, Zukunftstag).

She is trained as a biologist, museologist and environmental educator and loves to pass on her passion for science and nature topics to a wide audience.