DESIGN LAB: Nitrogen (2 of 4)

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Students will be able to 1) trace the movement of nitrogen through the nitrogen cycle; 2) define key vocabulary terms used to describe the nitrogen cycle; 3) describe how humans influence the nitrogen cycle.

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: The Nitrogen Cycle

In the first part of this DESIGN LAB, students developed a framework for materials recycling (what they will call "biogeochemical cycles" in this lesson), developed proficiency with testing strips that measure nitrate, nitrite, and ammonia, and made predictions about how the levels of these compounds will change over time in three unique model ecosystems.  This lesson pushes students to engage more deeply with the specific details of the nitrogen cycle.  What exactly is nitrogen?  What compounds does nitrogen form?  How do nitrogenous compounds move through living and physical systems?  What are some of the consequence of disruptions to this movement?

To better understand the nitrogen cycle, students will first complete a FLIPPED assignment outside of class that supports deeper understanding of nitrogen and the "recycling" of nitrogen.  In class, students will primarily engage with a jigsaw reading activity that will help the class understand biogeochemical cycles, fixation, assimilation, ammonification, nitrification, denitrification, and human changes to the nitrogen cycle. Finally, students will assess their understanding of the nitrogen cycle through a diagram labeling activity, as well as through a series of short, open-ended questions.  Students will understand the importance of nitrogen, how nitrogen cycles thought the environment, the name of key components of the nitrogen cycle, and how humans influence this cycle by the end of the lesson.

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.


  • 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.

FLIPPED CLASSROOM: What is the nitrogen cycle?

What is the purpose of this section?

Students develop a basic understanding of the nitrogen cycle through self-paced presentations. This is work done outside of regular class time. Students will norm understanding of this activity during class; theoretically, the FLIPPED model allows the teacher to better support students in making meaning because students will be able to quickly identify areas of confusion.  By the end of this activity, students should be able to broadly describe the movement of nitrogen through the nitrogen cycle.  Students should also be able to describe how ecosysteminteractions with nitrogen results in multiple compounds containing nitrogen that cycle through the environment in specific ways.  An example of such an interaction would be nitrifying bacteria.

What will the students do?

Students will examine the following two resources to answer two guiding questions:

  1. Why is nitrogen important?
  2. How does nitrogen cycle through the environment?

Clip 1: This animation provides context for understanding what nitrogen is and why it is important.  It also uses a baking analogy to explain why and how nitrogen forms various compounds as it cycles through the environment.  Fixation is the key vocabulary term.

Clip 2: This is another clip that provides context for the importance of nitrogen and examples of how nitrogen cycles.  It contains more advanced information than the previous clip and emphasizes the chemistry of nitrogen fixation.  This clip is an enrichment experience.  If students only watch the first clip they will have exposure to the key ideas for this lesson.

Students will answer the guiding questions as a single paragraph.  Within this paragraph, students are encouraged to use any new vocabulary that they have learned.  Some students with an interest in chemistry may want to write their entire summary from a chemistry perspective.  Teachers should explicitly communicate to students that the goal of these summaries is to describe the nitrogen cycle at the ecological level.  How do interactions make the nitrogen cycle possible?  Teachers should delve into the chemistry of the cycle with students only if they have demonstrated an understanding of the "big picture."

How will the teacher hold students accountable for this task?

As with previous FLIPPED assignments, the purpose here is to expose students to content; they will work to understand this content more deeply during class time.  However, if teachers need accountability measures to ensure that students are exposing themselves to this content in good faith, a teacher-facilitated online discussion is worth a try.

DATA COLLECTION: Testing strips

5 minutes

As an entrance routine for this DESIGN LAB, students groups formed during the previous lesson will take nitrate, nitrite, and ammonia readings from their model ecosystems.  Groups will record these reading in the data table from the prototype activity guide.  Students will use this data to inform work during the problem definition stage of the next DESIGN LAB lesson.  By the end of this section, students will have recorded one value for each compound.  Students do not yet analyze results.

EXPLAIN: Jigsaw reading

40 minutes

What is the purpose of this section?

Students discuss the FLIPPED content and then conduct a group “deep dive."  This deep dive consists of a jigsaw reading of an informational text followed by a short presentation to the class.  The teacher supports students’ exploration of an assigned aspect of the nitrogen cycle and also facilitates a whole group discussion of the nitrogen cycle.  By the end of this section students should be able to describe the changes that nitrogen must undergo to cycle through the environment. Students do not have to memorize all of the new vocabulary terms, but they should feel comfortable explaining the conceptual importance of each term.  For example, students do not have to "know" that nitrogen fixation involves a conversion from ammonium to nitrate; students should, however, be able to explain that unless certain specialized organisms convert nitrogen compounds from one form to another, nitrogen will not be "recycled."

TIMING NOTE: Suggested timing for this section is: five minutes for discussion of the FLIPPED work, 20 minutes for the jigsaw and presentation development, and 10 minutes for presentations, and five minutes for whole group discussion of ideas.

What will the students do?

First students participate in a short “recall” share of the FLIPPED assignment. 

  • What is the nitrogen cycle?  
  • How does nitrogen move through the environment?  
  • What parts of the nitrogen cycle are confusing?
  • Why do I think would happen to the planet if nitrogen could not cycle?

Students are then assigned to one of seven groups; each group receives a short reading passage. The topics for these passages are:

  • biogeochemical cycles
  • fixation
  • assimilation
  • ammonification
  • nitrification
  • denitrification
  • human changes

Each group will summarize the main ideas of the short reading and develop a "flash publication" of about TWO MINUTES.  This flash publication will retain the format used in other presentation activities from this unit:

  1. The presentation must begin with context.  What is the topic and why does it matter?
  2. The presentation must include a focus question.  What is the most important question to be able to answer regarding this topic?
  3. The presentation must include an evidence-based response to this focus question.  What data did the group gather and interpret to answer the focus question?
  4. The presentation must have at least one visual that helps learners understand content presented.  How might we use visualization to teach content in a way that verbal statements cannot?

Individual students should continue to work on previously established presentation goals.  At this point in the unit, teams may be ready to establish team collaboration goals.  An example might be "we want to finish our work early by five minutes so that we can practice our presentation" or "we want to split work into the development of visuals and the development of the spoken presentation."  Groups goals should be negotiated within each group with the support of the teacher.

What will the teacher do?

These readings can be complex for many students.  To best support students, differentiated versions of the reading should be developed ahead of time to meet student needs. These differentiated readings may include less complex language, diagrams, helpful illustrations, and fewer equations.  Students should be left to productively struggle with finding appropriate research resources.  A teacher may intervene if the students are truly unable to find resources.

Additionally, this presentation structure does not include a student feedback component.  Rather, the teacher will spend the bulk of whole group time assessing understanding of content.  What is the relationship between nitrification and ammonification?  Why can fertilizer use be destructive to ecosystem health? The teacher will need to keep careful records during the presentation, debrief and EVALUATE section to identify students that need additional support meeting lesson objectives.

EVALUATE: Check for understanding

10 minutes

What is the purpose of this section?

Students apply in-process understanding of the nitrogen cycle to a diagram problem and a series of questions.  The teacher gathers formative assessment data and supports struggling student.  By the end of this activity students should be able to comfortably label a nitrogen cycle diagram and explain the significance of ecosystems interactions in the nitrogen cycle.  They do not need to understand the actual chemical changes that occur, but students should be able why nitrogen may not cycle and the impacts of this lack of cycling.

What will the students do?

Students will complete a diagram of the nitrogen cycling and answer a series of summary questions. These are in the prototype activity guide.  Of the short answer questions, numbers 1, 3 5 and 6 will be the most important for students to understand in order to engage with the next lesson of this DESIGN LAB.  In order to design an effective nitrogen cycle from the model bacteria, fish, and plant ecosystems, students will need to understand how these ecosystems might interact to cycle nitrogen.

  1. Explain why bacteria are the most important part of the nitrogen cycle.
  2. If nearly 79% of the atmosphere is made of nitrogen, how could there be a shortage of nitrogen in soil?
  3. How do animals obtain usable nitrogen? Why is it important? 
  4. Give the two ways nitrogen can be fixated so plants can use it to grow. 
  5. Explain the problem if too much nitrogen enters an aquatic ecosystem.
  6. Summarize 3 ways that humans have an impact on the nitrogen cycle.

What will the teacher do?

The teacher will assist struggling students with mini-lesson reteaching or purposeful pairing with a peer.  Additionally, the teacher should challenge students that claim to “have it” by asking probing questions.  What would happen to this cycle if farmers used a pesticide that killed the bacteria?  By the end end of this EXIT, teachers should have a clear picture of students that understand the requirements for nitrogen cycle and students that struggle.  Struggling students will need remediation opportunities.  Edtech solutions can streamline this process.  So too can an interactive game.