The Nitrogen Cycle

Anita Edwards

IS 285 Meyer Levin, Brooklyn

Summer Research Program for Science Teachers

August 2008

Subject:  Earth Science

Grade Level: 8^th and 9^th

Unit: Humans in their Environment: Needs and Tradeoffs

Duration:  4 periods

Aim:  What is the nitrogen cycle and how can human activities modify this cycle? 

Objectives:

·         Demonstrate the various paths through which nitrogen can cycle between organisms and the physical environment  through the use of role play 

·         Construct a diagram of the nitrogen cycle and explain what it shows

·         Identify and discuss at least 3 examples of human actions that affect the nitrogen cycle

Vocabulary:  nitrogen cycle, nitrogen fixation, nitrification, denitrification, eutrophication, mineralization, nitrate, nitrite

Materials:

·         Student worksheet: The Nitrogen Cycle

·      * Student Worksheet: Traveling Nitrogen Passport Page (PDF)

·      11 Dice

·      11 Reservoir signs (atmosphere, surface water, rainwater, groundwater, fertilizers, soils, ocean, animal waste, dead plants and animals, live plants, live animals)

·     *11 Dice Codes  (one for each station) [PDF]

·      11 inkpads and small rubber stamps

·       LCD Projector and computer/laptop (for the projection of the nitrogen cycle diagram)

·       N-P-K soil test kits

·       3 types/brands of commercial fertilizers ( with different nitrogen concentrations)

·       Soil samples

 Procedure:

Engage (Day 1)

1.    Assess prior knowledge by introducing nitrogen.  Students may be asked:   

What is nitrogen?  Where on earth is it found?  Can it move from place to place or is it stationary? Why is nitrogen important?

2.    Explain that nitrogen can travel with the help of bacteria, plants, animals, water, and even lightning!  Inform them that they will pretend to be nitrogen atoms and engage in a role play to discover how nitrogen travels between the living and nonliving parts of the environment.

Explore (Day 1)

3.    Make large reservoir signs for  1.atmosphere, 2. surface water, 3.rainwater, 4.groundwater, 5.fertilizers, 6.soils, 7.ocean, 8.animal waste, 9.dead plants and animals, 10.live plants and 11.live animals.   Next, print the Dice Codes for the reservoir stations and cut them apart.  Set up the 11 stations around the classroom, making sure to supply a die, rubber stamp, inkpad, dice code, and reservoir sign for each station.

4.    Inform the students that they will simulate traveling through the nitrogen cycle by moving to the different reservoir stations around the room.  In order to do so, they must roll the die at each station to direct their path through this cycle.  At each station, they must stamp their nitrogen passport and indicate where their next destination will be and how they will get there.  This will be based on the results shown on the dice that they toss.

5.    Group the students so that there are 2-3 students at each station. Inform them that they will work individually and not as a group.  Therefore, each person must roll the die at each station visited.  You may choose to do a quick demonstration so that students understand how to cycle through the stations.  

Explain (Day 1)

6.    Once all the students have travelled enough times to fill their entire passport page, gather the students to facilitate a whole group discussion about their journey through the nitrogen cycle.  The following discussion questions may be used:

a)    Was everyone’s journey the same? Why or why not?

b)    Does the nitrogen cycle ever end?

c)    What are some of the reservoirs on Earth where nitrogen is found?

d)    What are some of the processes in which nitrogen can move from one reservoir to another?

Extend  (homework assignment)

7.    Draw and color a diagram to show your path through the nitrogen cycle.  Then, write a paragraph describing your journey.

* *  *  * *  *  

Engage (Day 2)

8.    Randomly call on a few students to read their paragraphs and show their diagrams of the nitrogen cycle.  This will serve as a brief review.   

Explore (Day 2)

9.    Distribute copies of the student worksheet: The Nitrogen Cycle. Project the color diagram of the nitrogen cycle using the LCD projector. The students can refer to the same diagram on their worksheet as key concepts about this cycle are discussed. 

Explain (Day 2)

10.  Divide students into cooperative learning groups and assess their understanding of the key concepts by having them read the introduction about the nitrogen cycle and answer the questions on the student worksheet. 

Extend  (Days 3 and 4)

11.  Take the students on an outdoor exploration to do soil sample investigations.  This can easily be done in the schoolyard /courtyard.  Students should be divided into groups of 4 and instructed to collect soil samples at various locations throughout the field.  The students will then analyze these samples using NPK soil testing kits to determine their concentration of nitrogen, phosphorus, and potassium.  Students should record their data in their science notebooks. Based on their findings students can make conclusions about the concentration of NPK in the soils and the plant growth observed at those locations. 

12.  The students should then be introduced to the fertilizer samples with varying amounts of NPK.  Based on the results of their soil sample study they should write an argument for or against the use of the fertilizers given to promote the growth of the plants in the field.

New York State Standards: 

Intermediate Level Core Curriculum

·         Standard 1: Scientific Inquiry

·         Standard 4:  The Living Environment (6.1c,7.2c,7.2d)

·         Standard 4:  The Physical Setting (2.2r)

·         Standard 6: Interconnectedness-Common Themes (6.1)

Physical Setting/ Earth Science Core Curriculum

·         Standards 1 and 6