With frequent attention in the news on nutrition and obesity, food can be a practical and engaging instructional context worthy of consideration in our classrooms. Students often lack basic information on where their food comes from; how it's produced, manufactured, and marketed; and the costs associated with these processes. Yet there is inherent interest among students in food and issues related to nutrition. These realizations helped to direct a recent project-based learning (PBL) experience that bridged the gap between farm, classroom, and even the lunchroom. The unit I describe here could be reproduced elsewhere but is meant more to inspire and instruct. Sometimes opportunities for educational innovation can be as close as the nearest lettuce leaf!
To help engage and inspire my students, I introduced them to Michael Pollan's book The Omnivore's Dilemma. Through a discussion of the issues in Pollan's book, students identified concerns about traditional food production and nutrition. With encouragement from me that we could design a PBL lesson with authentic, motivating, and meaningful elements, we began to address the issues raised.
Some students had previous experiences with growing crops using traditional soil gardens, so with funding from our Parent-Teacher-Student Association and advice from the local county agricultural extension agent, science students built four raised garden beds and planted tomatoes, eggplant, peppers, corn, and squash. After harvest, the produce was shared among students, faculty, and staff. These raised garden beds helped the students construct meaning using the knowledge and skills from agricultural science, mathematics, biology, and career and technical education. We moved on to a plan to construct a greenhouse, but even though school administrators and the superintendent approved the plan, city officials did not, citing local building regulations. Undaunted, the students next explored hydroponics as an alternative way to grow vegetables such as lettuce. In discussions with the high school's food service manager, the students learned that hydroponically grown lettuce was available in the cafeteria and were motivated to learn more about it.
Hydroponics is a method of growing plants using nutrient-enriched water without soil. It's gardening that is independent of external space and an outdoor growing season. Since hydroponics can be conducted indoors throughout the year, fresh, local produce is always available. Many hydroponics systems contain similar components, such as a structure for holding the plants, a reservoir of water containing nutrients, a method for getting the water to the roots of the plants, and a light system. This interest was easy for me to support because of the clear opportunities for learning basic science content, engineering principles, and a range of problem-solving scenarios.
For instance, hydroponics systems are a perfect vehicle for engaging students in learning and applying concepts from chemistry (e.g., pH, conductivity, nitrates, phosphates), physics (e.g., light – wavelengths, frequency, and intensity), and biology (e.g., photosynthesis, plant physiology, plant health). Students can also conduct research investigations by changing variables (e.g., the time the lights are on, different wavelengths of light, different concentrations of nutrient solutions). The relative ease of controlling and manipulating multiple variables that impact plant growth can make hydroponics a practical context for learning about and conducting investigations. In short, hydroponics is ideal as an integrated project that can be used in conjunction with a current curriculum.
With assistance from faculty at Virginia State University, students learned about multiple versions of commercially available hydroponics systems. With funding from the Falls Church Education Foundation and additional support from the local county agricultural agent, a hydroponics system would provide our school with a continuous supply of lettuce throughout the academic year and teach many valuable lessons in the process. The system adopted by our students is called the nutrient film technique (NFT). The NFT system provides a slow, steady stream of nutrient-rich water to plant roots. A combination of pumping and gravity draining is used to circulate the water through long trays. This system is beneficial because it promotes highly oxygenated roots, is easy to assemble, provides a constant flow of water with nutrients, and makes it easy to conduct root checks.
At the high school and the middle school, approximately 40 students manage three NFT units and perform duties that include seed germination, seedling transplant, making daily observations of plant health, mixing nutrient solutions, checking water pH and water levels in the reservoir, and monitoring light intensity and amount of time exposure. Students serve as the architects and managers of the hydroponics units, learn more about botany, and provide a supply of lettuce for use in our schools' cafeterias. Since 2017, when the hydroponics project started, over 200 pounds of lettuce have been harvested and served in the cafeterias.
Our local, hydroponically grown lettuce is fresh and of higher quality because it is consumed shortly after harvest. Fresh produce loses nutrients quickly, but locally grown food that is consumed soon after harvest retains its nutrients. Also, hydroponic lettuce is more nutritious than conventionally grown supermarket lettuce because it is fed optimal nutrition.
So, does a PBL experience help students achieve success with learning? Yes! Our students have made presentations to community and environmental groups, were interviewed on National Public Radio and a local TV news broadcast, and were featured in the Washington Post and the Falls Church News Press. The project earned acclaim by receiving the Innovation Award from GreenSchools and the Presidential Environmental Youth Award from the U.S. Environmental Protection Agency.
PETER M. MECCA, a biologist, science educator, Environmental Club sponsor, and Virginia SWCD Conservation Education Teacher of the Year, teaches at George Mason High School, Falls Church, VA 22043; e-mail: email@example.com.