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Students use data to discover cause of fish kill in aquaponics greenhouse built with CTA-Institute For Teaching Grant

Temecula Valley High School (TVHS) science teacher Toby Brannon made an announcement to his class of 59 students who attend his Biosustainability course; “First, I want to say that this event was my fault”. While he was attending a midweek conference, he received the unfortunate news about the dead tilapia in one of their four 275 gallon fish tanks. Students made some decisions that might have compromised the health of fish in a second tank.

The Biosustainability course was developed two years ago with the help of a $20,000.00 Institute for Teaching (IFT) Grant. The class discussion centered on the yet-to-be diagnosed issue in their #4 aquaponics tank, where 26 tilapia of varying size were found floating over two days. The class and club took in the news without fanfare; “We already learned something from our fish kill- we don’t have a protocol in place for this type of event” Brannon said.

Mr. Brannon had extended the short lab portion of the class for this discussion. Teams were then dispatched to the greenhouse to complete daily maintenance and to gather data on #4 that will inform their hypotheses about the loss.

In the greenhouse, rows of grow beds stretch the length of the structure, with four large fish tanks at the far end. The tanks, connected to a system of pumps, continuously circulate the water through the grow beds, feeding the crops with the nutrients produced by the fish. The loss of fish equates to a loss of nutrient production.

Student Henry Broadmax takes measurements in tank #4

Back at tank #4, TVHS student Henry Broadmix is measuring nitrate and Ph levels, gathering part of the data that students will use to inform their next steps. Because there is an inherent sense of urgency to discover the problem, students work quietly and diligently to gather the necessary readings.

Once gathered, the biosustainability students will use the data to form an action plan to address the tank issue. During the process Brannon is careful not to give students too much assistance; “There is never an inherently correct answer, it’s just students discovering how to solve whatever systemic issues we have, as we have them” he said.

Students’ work ethic and attitude in the class are proof of the efficacy of this student-centered methodology. Last year, the first class of biosustainability students wrote another successful IFT grant to bring solar power to the greenhouse. Due to the ongoing grant funding, this year’s students will have the opportunity to develop and build out this second solar project. This additional work will happen while continuing the learning and improvement of their greenhouse project.

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