Hydroponic System

by Özlem Saygın, Ph. D. (#Integrated STEM Teaching for Secondary Schools Rerun)

(2022 STEM Discovery Campaign-Scientix Competition 1: STEM Activities)

The activities of the Hydroponic System were implemented in 10th grade (age 16) in Antalya Erünal Sosyal Bilimler Lisesi, Turkey. We implemented the learning scenario between 08 March and 26 April 2022.

Global warming in the world, the inefficiency of agricultural lands, unbalanced increase in the world population, increase in food prices, and similar problems cause great problems in healthy and adequate nutrition. Landless farming methods which are applied to limited areas seek solutions to these problems. The aim of our activities was to learn about growing plants in the hydroponic system. So, students can grow plants in soilless conditions inside the buildings. Students researched necessary conditions for plant growth, the quality of water, essential minerals, and the importance of the wavelength of light. They tried to find solutions to the problems they faced.

Firstly, we prepared this learning scenario for Integrated STEM Teaching for Secondary Schools Rerun MOOC as a team. Then we improved and implemented it.

Our activities

Engage

Students were asked the following questions as real-world problems, respectively:

  • How can we meet our food needs if we face food shortages due to climate change?
  • How can we grow our vegetables in a drought?
  • Is soilless agriculture possible?
  • Which methods can be applied for the use of inorganic substances by producer organisms?

After the students’ preliminary information was revealed and their ideas were taken, the following videos were watched on the subject.

Explore

Students were divided into groups. By examining this website, they decided to do deep water culture.

The groups did internet research and watched videos both in English and Turkish about the hydroponic system setup they have chosen. They tried to find answers to these questions:

– Which plant species can be grown in hydroponic water culture?

– What nutrients do plants need? Do the nutrients need to change according to the plant species?

-What should be pH, EC, and temperature of water for their plants?

Students wrote the list of materials they would need. We bought A and B nutrients, pH meter, EC meter, pH reducer, perforated pots, air stones, air motor, air pipe, storage containers, perlite, LED, and Arduio set.

Explain

Students discussed the causes and consequences of global climate change. They brought their bills of electricity, water, and natural gas. They asked their parents how many kilometers a month they traveled by car and motorbike. They measured the carbon footprint of their family at this link.

They researched what they can do to reduce their carbon footprints and made a list.

  • The distances that can be traveled on foot should be covered by walking, if there are suitable conditions, by using a bicycle.
  • Reducing waste, consuming products that can be consumed without packaging, and paying attention to recycling.
  • Using solar energy instead of natural gas and electricity.
  • To use renewable energy for electricity, to prefer energy-saving light bulbs, refrigerators, and air conditioners.
  • To travel by public transport as much as possible.
  • Hang dry the laundry instead of using a dryer.
  • Do not run your dishwasher before it is full.
  • You can water your plants in the garden with the water you use for washing fruits and vegetables.
  • When you are not using your electronic devices such as computers and televisions, be sure to turn them off and unplug them.
  • Buy as much food as you need and put as much food on your plate as you can eat. Try not to create food waste.
  • Instead of buying bottled water, carry flasks.
  • Use a water-saving showerhead.

Elaborate

Students set up their hydroponic system as groups.

Materials:

  • Lettuce etc. seedlings
  • Perforated pots for seedlings
  • Styrofoam (3 mm thick)
  • Deep, opaque storage container (10-25 L)
  • Airstone
  • Aquarium air motor
  • Water pipe
  • Aquarium check valve
  • A and B nutrients
  • pH meter
  • pH reducer
  • Conductivity (EC) meter
  • Thermometer
  • Injector
  • Utility knife
  • LED
  • Arduino set
  • Perlite

Students cut styrofoam suitable for the storage container. They drilled round holes for the perforated pots on the styrofoam. They cut the corner of the Styrofoam, so the water hose could pass. They measured the liter of water while they were putting it in the storage container, then placed the air motor and airstone. They used a check valve to prevent water from entering the air motor. They mounted the air motor high above the system. They put 2 ml of each A and B nutrient per liter. Then, we adjusted the EC=0.8 mS/cm and pH=6.0, these values are for lettuce. Values of water should be adjusted according to the plant species. Students put seedlings in the perforated pots and filled them with perlite. They sat the pots on styrofoam.

In the chemistry lesson, students learned which minerals plants need and how to calculate the ratios of chemicals in a mixture.

In the physic lesson, students investigated the effect of the wavelength of light on plant growth. They used LED lighting with an intense red light so that the plants can grow faster in a low light environment. Then, they programmed its timing to be ON for 16 hours (lighting) and to be OFF for 8 hours (dark) via the Arduino.

Students measured and recorded EC, pH, and temperature of the water every day.  We made the necessary adjustments. The problem we faced was that the pH was rising every day. We added 20% nitric acid for reducing it. Then we used purified water instead of tap water because the EC of tap water was high. Using purified water slowed pH to rise. After 5 weeks, our lettuces grew enough, we harvested and ate them.

In the mathematics lesson, students drew graphics of daily pH increases and the temperature of the water.

The video of the project presentation can be seen here.

We used a self-assessment form for evaluation. In addition, students replied to these questions in the form:

  • What problems did you encounter while installing the hydroponic system and growing your plants?
  • How did you find solutions to these problems?
  • What can you do to improve your design?
  • Are you considering using the hydroponic system in your home?

Students exhibited their projects at the Science Fair of our school on 27th April 2022.

Teachers used the teacher assessment form for evaluating the performance of students.

Connection to STEM Careers

Our activities are associated with professional areas such as environmental engineering, biochemistry, biotechnology, management of biological resources, agricultural engineering, and computer engineering. Students watched a video of the plant factory in our city.

21st Century Skills

Collaboration, communication, productivity, critical thinking, problem-solving, information and technology literacy, initiative, and social skills.

Conclusion

This project is an effective STEM project. It promotes entrepreneurship. Students enjoyed trying something new and they realized that growing plants takes effort. They had to devote time to their projects every day, but some students found it difficult. They learned the importance of recording data while doing a scientific study. They presented their projects with pride and enthusiasm at the science fair. Growing plants in hydroponics are not very common, so it attracted a lot of attention. This project needs a budget. The project can be continuously developed, and new applications can be tried in time.

Our Team

Biology: Özlem Saygın, PhD.

Chemistry: Ayşegül Gençer, PhD.

Mathematics and Information Technologies: D. Aslı Kaplan Yaşkaya

Physic: Şerife Demirel

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