DESIGN LAB: Nitrogen (1 of 4)
Lesson 15 of 24
Objective: Students will be able to 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; and 3) predict how levels of ammonia, nitrate, and nitrite will change over time.
Students developed an understanding of soil in the previous series of lessons. This DESIGN LAB invites students to dig deeper. What specifically makes soil healthy? What exactly do we protect when we protect soil? How do the components of soil impact ecosystems? How do ecosystems work together to maintain healthy soil? What happens to soil when healthy ecosystem interactions do not take place? How do our food choices help or hurt the environment?
There are many ways to answer such questions. This DESIGN LAB focuses on the nitrogen cycle. Students will learn about the nitrogen cycle, develop proficiency with measurement tools, take an engineering design approach to understand how the cycle optimally operates, and engage in traditional scientific inquiry (experimental design) to obtain information that will be necessary for evaluation of their design ideas. By the end of this lesson sequence students will have a deeper understanding of the connections among soil health, nutrient cycling, ecosystem interactions, and human developed systems, such as the industrial food system.
During FIELD STUDY, students gained some familiarity with the concepts of this lab through exploration of Oko Farms, an aquaponics farm in Bushwick. However, rather than a big picture overview of interacting aquatic and terrestrial ecosystems, this DESIGN LAB focuses on the chemical structures that allow aquaponics systems to function. For most students, the study of nitrogen will be a new experience, even if they were exposed to the nitrogen cycle during previous courses. Most of my students can describe what happens to water and carbon as they cycle; nitrogen is another story. This year, for instance, only about 10% of my students understood that nitrogen is extremely common as the majority gas in air. As such, do not assume that students are familiar with the nitrogen cycle, even if they claim that they "learned it" in a previous class.
In this first lesson, students explore the idea of nitrogen as a recyclable element vital for healthy ecosystems. Students also learn how to measure levels of ammonia, nitrate, and nitrate, elements of the nitrogen cycle. By the end of this lesson, students should be able to articulate how nitrogen cycles through the environment and should also be able to measure levels of ammonia, nitrate, and nitrate in an aqueous solution. Both outcomes will be necessary for success with the remainder of the DESIGN LAB.
By the end of this DESIGN LAB sequence, successful students will have met the following objectives:
- explain the role of recycling in biogeochemical cycles
- use test strips to measure levels of ammonia, nitrate, and nitrite in various aquatic environments
- predict how levels of ammonia, nitrate, and nitrite will change over time.
- trace the movement of nitrogen through the nitrogen cycle
- define key vocabulary terms used to describe the nitrogen cycle
- describe how humans influence the nitrogen cycle
- engage in an engineering design thinking cycle to develop a functional nitrogen cycle prototype from unique model ecoystems.
- test nitrogen cycle prototypes through peer review
- iterate prototype designs
- develop an experimental design to assess the effective of design prototypes
- 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.
- The other included documents consist of alternate activities that were considered for this lesson sequence. They might work better for some educators.
What is the purpose of this section?
Students surface prior knowledge about the role of materials cycles in biological and geological systems. The teacher collects formative assessment data to determine students’ readiness to participate in the nitrogen design lab. By the end of this activity, students should be able to broadly explain how materials cycle and the consequence of disrupted cycling.
What will the students do?
Students read a short passage about the recycling of materials that occurs through biological and geological processes. They then respond to prompts that check prior knowledge and connect to environmental science concepts.
Prior knowledge check
- Make a list of things that can be recycled.
- Use these lists as a resource and explain how we manufacture new products from recycled materials
Hint: If you are struggling, learn about a Sunset Park recycling center from the clip below.
DIFFERENTIATION NOTE: For classes with limited prior knowledge or a high concentration of students that benefit from visuals before reading, it might be better to show the above clip to the entire class before introducing the text. If possible, this footage should be from a local recycling center. It will be especially valuable if the teacher captures this footage, as this builds a real connection to the local community.
Environmental concepts connection:
- What happens if one of the steps in a cycle is missing?
- How do different organisms rely on each other to complete these cycles?
- Could there be a worldwide food shortage if certain bacteria disappear from the soil
Students discuss responses in small groups and then share out ideas through a short, whole group discussion.
What will the teacher do?
The teacher will look for evidence that students understand the process and purpose of materials cycling. Does the student understand that materials such as carbon and nitrogen cycle through biological and geological systems? Can the student explain the downstream consequences of a disruption in materials cycling? This will be done through classroom observation during student work time as well as through brief whole class discussion of ideas. The idea that materials are recycled like a plastic bottle is important for this DESIGN LAB. Without a solid grasp of this idea, students will not be able to fully engage in subsequent activities.
EXPLORE: Inputs and outputs
What is the purpose of this section?
Students work in teams at one of three stations to explore how levels of ammonia, nitrate, and nitrate will change over time in an aquatic environment. The teacher frames the activity by explaining that students will explore the nitrogen cycle over the next few lessons by considering how it might cycle among various model ecosystems. In this particular activity, students will learn how to measure nitrogen compounds in these model ecosystems. By the end of this activity, students will be able to measure ammonia, nitrate, and nitrate in three different model ecosystems. They will also be able to make evidence-based predictions about how these levels will change over.
What will the students do?
Students work in teams at one of three stations: plant, bacteria, or fish. (Depending on class size, two to three groups will be working at each plant, bacteria, or fish station.) The prototype activity guide contains directions for students to follow to establish a working lab station as well as a table to record data. Regardless of the assigned station, student groups follow three general steps:
- Construct a working lab station using conditioned water. All materials for each station are on a lab demonstration table at the front of the classroom.
- Collect baseline readings for ammonia, nitrate, and nitrite and record in the provided data table.
- Predict how the station will change over time. How will levels of ammonia, nitrate, and nitrite change? How will these changes impact bacteria, fish, or plants? Support claims with evidence.
- Students may want to conduct additional research before making a prediction. This is encouraged, but the request should come from students. They are the primary scientists in this experience. The teacher must remain in a support role. Guiding questions for these predictions for each model ecosystem are in the prototype activity guide.
The majority of this activity is an opportunity for students to engage in "structured play." Students have a set of objectives that include putting together a lab station and proficiently using lab measurement tools. Students groups are given freedom to self-organize as much as possible during this work. Students are free to speak with other groups, make mistakes, try different methods of measurements, investigate lab stations setups, and conduct limited internet research to better understand a topic.
What will the teacher do?
My primary role is to support students in exploring their station. This might include obtaining resources, conducting brief mini-lessons for students that have never used testing strips, or asking clarifying and probing questions. Each group should end up with a prediction based on evidence and each student should understand how to collect data with the testing strips. The only time the teacher should intervene in student group work is if groups engage in a procedures that poses a safety risk or will damage needed classroom materials. As such, a key teacher move is to allow students to make mistakes and to facilitate peer interactions that allow students to learn from these mistakes. Students ownership of this process dramatically decreases when students feel like they are simply following a script. Of course, this does not mean that student mistakes should go without feedback. If peer groups do not appropriately correct mistakes, the teacher must intervene with corrective feedback.
EXIT: We think...because
What is the purpose of this EXIT?
First, the teacher models appropriate lab cleanup procedures and student teams cleanup lab stations. Names of groups members go on masking tape attached to each model ecosystem. Model ecoystems are stored in labeled shelved in a cabinet in the back fo the classroom. Testing materials go back to the lab demonstration table at the front of the room.
Next, the teacher facilitates a group share of prediction ideas. What will happen to the nitrate, nitrite, and ammonia levels in each of the model ecosystems over time? Why? The teacher records student predictions on the whiteboard or in a digital document. Time permitting, students have an opportunity to challenge each other's predictions by using evidence from the Explore activity. Common examples of a student group predictions were that the fish would produce a lot of waste and that levels for all compounds would go up or the plants will not have an increase in measured nitrogen compounds because they help to clean the air. The accuracy of these predictions should not be assessed in this first lesson, but students do need to track predictions. Students will amend initial prediction based on the results of future activities in this lesson sequence.
TIMING NOTE: Lab cleanup must be modeled explicitly by the teacher. Although it may seem obvious where materials go, students will not always intuit the organizational scheme for materials. Teachers can reduce wasted time and student frustration by taking time to model end of lab procedures.