The Arizona STEM Acceleration Project

Kratky Hydroponics

Kratky

Hydroponics

A 6th-8th grade STEM lesson

Author:

Mike Amato

Sarah Genise�

Date: 04/20/2023

Notes for teachers

Depending on the academic level of students, some prep on the teacher’s side might be more or less. An example of this would be using the hole saw. If the teacher does not feel comfortable having students use the hole saw, then this is a step that needs to be prepared.

List of Materials

• 1-gallon bucket with lid
• Rockwool cube or rapid rooter
• Bell pepper seedling
• Nutrient Solution - FloraBloom, FloraMicro, and FloraGrow were used in this lesson. Other hydroponic solutions can be used as well.
• pH testing kit
• pH up & pH down
• Scissors
• Marker
• Ruler
• Hole saw drill bits
• Drill
• Net cup
• Aeration pump

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Standards

6.RP.A.1: Use ratios to describe proportional relationships.

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7.RP.A.3: Apply proportional relationships to solve multistep ratio and percent problems.

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RST.6-8.3 - Follow precisely a multistep procedure when carrying out experiments, taking measurements, or performing technical tasks.

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RST.6-8.4 - Determine the meaning of symbols, key terms, and other domain-specific words and phrases as they are used in a specific scientific or technical context relevant to grades 6-8 texts and topics.

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Standards

MS-LS1-3: Plan and conduct an investigation to provide evidence that feedback loops maintain homeostasis

MS-ESS2-5: Develop and use a model to describe how the cycling of matter (e.g., water, carbon, nitrogen) in and out of the atmosphere and soil involves interactions among the biosphere, geosphere, hydrosphere, and atmosphere.

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Objectives:

Students will be able to construct a Kratky Bin hydroponic system and grow bell peppers using a 1-gallon bucket by following step-by-step directions.

Students will use ratio and proportional reasoning to add the correct amount of nutrients to the Kratky bins.

Agenda (50 minutes)

This lesson is designed for a 50-minute class period.

It is possible that this lesson needs to be broken into two sections

Prep time (10-15 minutes)

Introduction (5 minutes)

Activity (35 minutes)

Conclusion (10 minutes)

Intro

1. Start by explaining the benefits of hydroponic gardening, such as saving water, space, and time, and producing healthier plants. (The information below may be reproduced on a worksheet, Google Slide, or added into a discussion. This is up to the teacher’s discretion)�
2. Discuss the Kratky Bin method of hydroponics and how it works.��
3. Explain the materials required for building a Kratky Bin hydroponic system (i.e. if students have not used a hole saw drill bit, give a short demonstration on how it works and how to find the correct size). Additionally, go over appropriate safety protocols for using tools.

Hands-on Activity Instructions

1. Distribute the materials required for constructing the Kratky Bin hydroponic system.�
2. Have the students measure and mark the water level on the bucket using a ruler and marker. For this activity, students will be marking one gallon.�
3. Drill a hole in the lid of the bucket that is the same size as the net cup. The net cup should sit inside the lid of the bin but it should not fall through.�
4. Insert the rockwool cube or rapid rooter into the net cup.�
5. Plant the bell pepper seedling in the center of the rockwool cube or rapid rooter.

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Hands-on Activity Instructions

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1. Test the pH of the nutrient solution using the pH testing kit and adjust if necessary using pH Down and pH Up.�
2. Place aeration pump inside the bin. Plug into the wall. You should see bubbles in the water if the pump is working correctly.�
3. Place the lid on the bucket and secure it tightly.�
4. Place the bucket in a sunny location.�
5. Monitor the water level and nutrient solution pH regularly.

Assessment

1. Observe students as they construct the Kratky Bin hydroponic system and grow bell peppers using the system. This will assess their ability to follow instructions, handle materials safely, and demonstrate proper use of equipment�
2. Give students a recording sheet for recording the pH and nutrients. Monitor and make sure the students are properly calculating the nutrients needed for the bin (example: if the bottle of FloraMicro calls for 3 tsp per ½ gallon and we have a 1 gallon bucket, how many tsps do we need?)

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Differentiation

Bell Pepper Growth Observation Journal - ��If students are having trouble understanding the step-by-step process, break it down into smaller chunks. Assign the student a particular job and/or partner student with a team who will assist them.

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Remediation

Extension/Enrichment

Students can research different hydroponic systems and compare them with the Kratky Bin method. They can also investigate the advantages and disadvantages of using hydroponics over traditional soil-based agriculture.

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Have students calculate what the ratio of nutrients would be for various different plants.