DESIGN LAB: Nitrogen (4 of 4)

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Students will be able to 1) test nitrogen cycle prototypes through peer review; 2) iterate prototype designs; 3) develop an experimental design to assess the effective of design prototypes; and 4) connect potential experimental outcomes to modern agricultural practices.

Big Idea

A functional nitrogen cycle is an essential part of healthy agricultural systems. How might we use models to help us understand how the nitrogen cycle becomes disrupted and what might be done to prevent disruption?

FRAME: Design meets experimental design

So far in this DESIGN LAB, students have developed a framework for materials recycling, developed proficiency with testing strips that measure nitrate, nitrite, and ammonia, made predictions about how the levels of these compounds would change over time in model ecosystems, developed familiarity with key terms used to describe the nitrogen cycle, described how humans can impact the nitrogen cycle, and prototyped functional nitrogen cycle sytems from model ecosystems.  For this final DESIGN LAB, students students test and iterate prototypes that address the overarching design challenge: how might we design a functional nitrogen cycle with our model ecosystems to understand factors that disrupt the nitrogen cycle, and, by extension, apply insights to prevent future disruptions?  

In this lesson, students will finish building prototypes, test these prototypes through a baby shark tank, iterate, develop experiments to test the effectiveness of prototypes, and connection future experimental results to problems caused by industrial agriculture.  By the end of this lesson, students will have presented a prototype, given and received feedback, iterated, developed an experiment to test the effectiveness of prototypes, and connected potential results to real world impacts of modern agriculture.

By the end of this DESIGN LAB sequence, successful students will have met the following objectives:

  1. explain the role of recycling in biogeochemical cycles
  2. use test strips to measure levels of ammonia, nitrate, and nitrite in various aquatic environments
  3. predict how levels of ammonia, nitrate, and nitrite will change over time.
  4. trace the movement of nitrogen through the nitrogen cycle
  5. define key vocabulary terms used to describe the nitrogen cycle
  6. describe how humans influence the nitrogen cycle
  7. engage in an engineering design thinking cycle to develop a functional nitrogen cycle prototype from unique model ecoystems.
  8. test nitrogen cycle prototypes through peer review
  9. iterate prototype designs
  10. develop an experimental design to assess the effective of design prototypes
  11. connect potential experimental outcomes to modern agricultural practices.

FEEDBACK NOTE: Teacher that want to provide feedback to groups about their engineering design thinking process might use this rubric from Unit 0 or this series of rubrics from the Henry Ford Learning Institute.


  • The materials for this lab were purchased from Carolina.  
  • The included prototype activity guide is a basic template that might be differentiated for a a group of diverse learners.

PROTOTYPING (2 of 2): Is aquaponics the only viable solution?

15 minutes

What is the purpose of this section

Students continue to build out the physical prototypes that designed in the previous lesson. Teacher will support this build process with materials, suggestions, probing questions, and framing of prototypes as opportunities to learn from failure.  By the end of this activity student groups will have physical prototypes to test with other students.  This prototyping stage should ideally be the implementation of the solution idea.  However, students groups will iterate on the fly and should be encouraged to do so, as long as iterations are made through a collaborative process.

What will students do?

Students will first revisit design ideas shared during the previous exit.  Many groups will share some variation of an aquaponics system. but teams should not feel pressured to adopt aquaponics as the "right" solution; explicit teacher framing might be necessary. Students may only use provided materials (the three model ecosystems and additional lab equipment).  Students may also collaborate with other teams if they believe that they can build a functional nitrogen cycle by combining all three model ecosystems.  

What will the teacher do?

As with the previous prototyping activity, student teams will engage in focused chaos.  The most important teacher move in this section is to support students' needs.  This might include retrieving materials, testing sections of prototype design for failures, encouraging students groups to collaborate with each other, asking probing questions, providing work space, and assisting with actual construction.  Many students will want to fully test the prototypes so that they are "ready" for the baby shark tank.  However, the goal of the TESTING phase is to give and receive feedback during public presentation of prototypes that are very likely to fail.  This is a norm that we have developed and revisited throughout this year.  Students, however, will likely need a reminder.

TESTING: Sharks in the fish tank

12 minutes

What is the purpose of this section?

Students engage in a baby shark tank TEST session.  One student group present the prototype to another group that provides feedback.  The groups then switch.  A protocol for this activity is in the RESOURCES section.   By the end of this activity, student groups should have presented a prototype, received warm and cool feedback, and also provided feedback to another team.

What will students do?

First, the presenting team delivers a two minute pitch. The pitch will answer the following questions:

  • Why did your group develop a prototype? What is the need for this model?
  • What solution ideas did you group consider?
  • What are the key features of the current prototype?
  • Why do you think the current prototype will result in a complete the nitrogen cycle?

Once students have pitched, the sharks provide warm and cool feedback.  The purpose of this feedback is to give the presenting team actionable feedback that will improve the prototype. (These are, after all, baby sharks.)  Answers to the following questions are the suggested format of this feedback:

  1. What do you think will work? 
  2. What do you think will not work?
  3. How can this group improve its prototype?

What will the teacher do?

The teacher will facilitate this process when necessary.  The primary teacher move will be to provide feedback about feedback if students do not provide constructive comments aligned to the design task of developing a functional nitrogen cycle from three model ecosystems. Feedback should probe students design ideas.  Many groups will have had difficulty with water flow.  Feedback to help this issue is appropriate.  However feedback that is only about the mechanics of water flow is not acceptable; feedback should also include questioning of purpose.  Why do you think this prototype solves the design challenge? How do you know?

ITERATION: Learning from failures

15 minutes

What is the purpose of this section?

During this iteration activity, students revise prototypes for final testing.  Revisions should align to provided feedback and to ideas developed by the group in response to feedback.  By the end of this activity, students should have made adjustments to prototypes that address issues raised during the feedback process.  Students should be able to explain these choices in terms of the nitrogen cycle; explanations that only align to the mechanics of the prototype are not sufficient.  For instance, if a student team needs to adjust water flow, they need to be able to explain why they want water to flow from one model ecosystem to another.

What will students do?

Students will essentially engage in the PROTOTYPE stage again.  This time they will make major or minor adjustments to prototype design.  The goal is for students to have a final prototype that they will test through data collection.  

What will the teacher do?

The teacher will support this work in any way necessary.  Students are likely to be very self-sufficient in this activity.  If student appear able to self-regulate during this activity, the teacher should start to prepare groups for the experimental design framework of the FINAL TEST activity.  Why do you think connecting the three model ecosystems will result in a functional nitrogen cycle?  If your final test suggests that your prototype works, what are the implications of your prototype for modern agricultural systems?  What might the agriculture industry learn from your work?  

FINAL TEST: Scientific experiments support design effectiveness

10 minutes

What is the purpose of this section?

Students design a simple experiment to determine the effectiveness of their final prototype.  By the end of this section, student groups will have determined how they will measure levels of ammonia, nitrate, and nitrate over the next week.  Once students have collected this data they will analyze and draw conclusion about the effectiveness of their prototype.

What will students do?

Students will review a "Design Report" overview from the prototype activity guide. This design report will consist of the following section:

  • Background information
  • Hypothesis
  • Materials
  • Procedure
  • Results
  • Analysis
  • Conclusion

Students will have a week to collect data and submit an individual product.  The final Design Report will be assessed for mastery against the objectives for the DESIGN LAB lesson sequence.  This Design Report is essentially a lab report.  However, its purpose is to assess the effectiveness of a prototype design.  As such, this is a lab report that marries the engineering design framework with the traditional scientific method.

What will the teacher do?

The teacher frames the activity and primarily assesses students ability to develop a hypothesis. Student groups struggling with a hypothesis about how levels of ammonia, nitrate, and nitrate will change over time indicate a lack of understanding about the nitrogen cycle. Teachers should focus feedback and intervention efforts here.

DEBRIEF: Summarizing the DESIGN LAB and making connections

3 minutes

For this DEBRIEF, students will answer summary questions from the prototype activity guide and make connections to industrial agriculture.  The teacher will collect responses and assess students' ability to articulate how ecosystem interactions are necessary for a functional nitrogen cycle as well as students ability to relate human impacts, especially impacts of agriculture, to this DESIGN LAB. Corrective feedback should be given immediately as the next series of lessons examine agricultural technology and sustainability.  An understanding of the relationship between human impacts and the nitrogen cycle will make both experiences more enriching for students.