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Sustainable STEM: Hydroponics Systems

Updated: Aug 18, 2022

Classroom Kits with the materials to run this activity are available NOW!


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The word hydroponics is derived from two Greek words- hydro water -ponics to work/labor; and is a purposeful process for growing plants without soil. Teaching and learning about hydroponics is a great approach to integrate science and engineering in the classroom because students can learn about:

  • the biological systems of plants (e.g., their growth cycles, their requirements for survival), and

  • the technological systems of hydroponics (e.g., what materials and simple/advanced technologies are needed to control the environment that supports plant growth).


Want a quick summary? Check out this video at




Today, the field of hydroponics is certainly turning heads. Check out how the National Agricultural Library provides many resources alongside a list of research institutions working on sustainable hydroponics throughout the US.


What is the future of hydroponics in schools? This school has a hydroponic farm in the cafeteria!



Perhaps your school will be the next big innovator in this growing industry!


What Plants to Grow

You can use any seeds, but some plants are much easier to grow hydroponically than others. For an activity like this, you may want to use some of the plants that do not have a lot of mass to them. Lettuce is easy for your students compared to an evergreen shrub like rosemary, but there is ample opportunity to add some challenge! Check out some good candidate for this activity below:



Hydroponic Nutrient Selection


A number of options are available for the nutrient solution because plants cannot thrive on nutrient-deficit water and sunlight alone. If you have access to a freshwater fish tank, that is an easy and inexpensive nutrient solution- fish waste is an excellent fertilizer! Another option is a DIY approach. Creating your own solution can be a great chemistry integration activity. If you do not have any fish nearby and you do not want to make your own nutrient solution, you can use an assortment of nutrient solutions available like Urban Lead Hydroponic Plant Food or your hydroponic-related small businesses.


Hydroponic Prototype


In this activity, we are creating rudimentary hydroponic systems that students can design in the classroom and then take home. Additionally, the materials used are eco friendly, compostable, and/or recyclable! You can feel more at ease knowing 1) no single-use plastic was needed to build the hydroponic systems and 2) kids are using and learning about sustainable materials.


Let us go ahead and build a rudimentary hydroponic system! For this challenge, we made sure all of the materials were eco friendly and provide the environment required to keep plants alive. You can purchase all of the materials in our single kit or classroom kit. If you choose to collect these items on your own, please make eco conscious decisions.

  • Cup

  • Lid

  • Cotton Ball

  • Brown paper towel or coffee filters

  • Closed container or compostable resealable bag

  • Seeds (See list above of good plant candidates for this activity.) We are using lettuce seeds here.

  • Compostable container to hold seedlings

  • Bamboo-based Straw

  • Nutrient Solution

  • Scissors or utility knife


Scissors, bag of lettuce seeds, bamboo straw, cotton ball, coffee filter, ziploc bag
Materials for the project. All single use items are compostable!

Instructions

  1. Germinate the seeds in a damp coffee filter or brown paper towel. You can use a white paper towel too, but I find that the tiny hairs on the emerging seedlings tend to grow into the white paper towels and are damaged when you try to move them.

  2. Place coffee filter in a resealable bag to create a greenhouse effect. The length of germination time depends on what plants are used (1 to 5 days).

  3. Soak a cotton ball in a diluted hydroponic solution and place the seeds partly in the cotton ball.

  4. Select a compostable or recyclable container that can hold water and has a lid.

  5. If you are not using a container from our kit, then cut a small hole in the lid of a container you have chosen that will firmly hold the cotton ball and seedlings. The containers we use already have a hole at the top and so you do not need to cut.

  6. Cut a second hole to insert the compostable coffee-based straw or a straw of your choosing.

  7. Fill the container with water and a dilute hydroponic solution so that the solution touches the bottom of the cotton ball. Secure the lid of the container.

  8. Students should blow air through the straw and into the hydroponic system approximately 1-2 times a day to aerate the water. For young students, we recommend you draw an arrow on the straw to show students which way to blow air!

  9. Students may take their hydroponic system home with a note to parents on the compostable/recyclability of the hydroponic system when the plants have matured. The nutrient solution should be changed every 7 to 14 days.

A compostable cup and compostable straw. The cup has water in it and a cotton ball is at the top. There are several seedlings growing from the cotton ball
A hydroponics project for young students. Look closely and you can see the root system in the water!

Is it Compostable?


Depends on what materials you are using. With our kit, everything is compostable! This is the compost of our project (with some additional overripe cucumbers and tomatoes from the garden). The cups and lids need a commercial composter as opposed to a typical backyard or school garden composter. Not everyone has a commercial composter that is local, so if you send us the cups back after the activity is done, we will compost them for you. Send us an email at contact@benplusstem.com for more info.


A bowl of compost
Composted materials from the hydroponics project


Hydroponic Design Challenge


There are many ways we can innovate this simple lesson. Here are a few examples:

  • Challenge students to develop a larger hydroponic system as their plants grow (still using eco friendly materials)

  • Experiment with different plant species

  • Experiment with different grow methods. For example, plants with more light vs. less light; no aeration vs. aeration with straw; hydroponic plants vs. plants in soil

  • Turn this into a phytoremediation activity by adding food dye into the hydroponic solution

  • Brainstorm how this technology can be used to increase food security in local, regional, national, and global communities


Young girl is blowing air into a cup of water with plants growing at the top of the cup
Child with hydroponics

Once your students make their prototypes, we would love for you to share them with us at Letters to Ben or share with us on Facebook, Twitter, and Instagram.


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