Expanding the View of Nitrogen Cycling

Background for Teachers

In this activity you will be dialing out the focus from what is outside the classroom to a more general look at the nitrogen cycle. The nitrogen cycle is a complex biogeochemical cycle. There are many forms of nitrogen and chemical notation of each can be a challenge. Because of that you should use as many different mechanisms as you feel are necessary to expose, but not overwhelm, your students the nitrogen cycle.  There are numerous nitrogen cycle diagrams in textbooks and on the Web that give the basics (this is the same figure as was in the last activity):

But, none that deal specifically with our landscape.  It is important that students put the nitrogen cycle into the context of the local landscape, and that they understand the nitrogen cycle in their own words. This activity follows the more locally-specific Activity 1 and gives the students exposure to the whole nitrogen cycle.

The students should add information about the nitrogen cycle to their diagrams from Activity 1.


Students understand:

  • The basic nitrogen cycle
  • That there are different forms of nitrogen
  • The role microorganisms play in changing the forms of nitrogen
  • The importance of nitrogen to living things
  • That plants and animals can use only certain forms of nitrogen
  • The natural and human-made inputs to the nitrogen cycle


  • Students will add to the nitrogen diagram that they began in the last activity.

Where does this lesson happen in the Project?

This is the second activity in the first Unit.

Getting Ready

Review the nitrogen diagram that the students created in the first Activity.

Explain that, while the cycling of nitrate in forested watersheds is the part of the nitrogen cycle that is most important to our research, the students will need to understand the nitrogen cycle and that they will be adding to their nitrogen cycle for a more complete reference diagram for the class to use while they are working on this project.


  • Visionlearning: The Nitrogen Cycle: Of Microbes and Men
  • The Nitrogen Cycle
  • Student nitrogen diagram from Activity 1

Student Prerequisites

  • Students should be able to explain a natural cycle.
  • Students should understand that chemical elements, like nitrogen, exist in a closed system. This is the basis for the key concept of conservation of mass. Nitrogen can neither be created nor destroyed, but it is cycled.

Time Needed

Two class periods (one for reading and adding to individual nitrogen cycles, one for adding to the class nitrogen cycle)

Doing the Activity

Students read the following two resources:

  • Visionlearning: The Nitrogen Cycle: Of Microbes and Men
  • The Nitrogen Cycle

Students add to their own diagram (from Activity 1) as they are reading.

Students then share the additions that they made and,

Using the information from these resources students will add to the classroom nitrogen cycle- to be used as a reference as this project moves forward.

Additionally, you may want your students to watch a Nitrogen cycle video such as: http://www.youtube.com/watch?v=3UpXYS53nq0&feature=endscreen&NR=1

TutorVista has a nice overview: http://www.tutorvista.com/content/biology/biology-iv/ecosystem/nitrogen-cycle.php



Have your students draw one plausible and one implausible path for a nitrogen atom to take. The students can share these and correct the implausible paths and explain why the plausible ones are credible.

Have your students play the Travelling Nitrogen game. Listen for discrepancies in the way students are moving (according to their dice rolls) and have them hand in their travelogue, making sure it is consistent with the nitrogen cycle.


Have students explain the nitrogen cycle to their parents, siblings or another class.

Lesson Extensions and Supplements

Students critique nitrogen cycle videos on YouTube.

Students make a nitrogen cycle video or song of their own

Students read: Hubbard Brook Research Foundation’s Nitrogen Pollution: From the Sources to the Sea (2-page fact sheet, there is also a 29-page document available)

Ask students to alter a condition in the cycle… decrease the number of nitrifying bacteria, increase the input of urea, and discuss how this may change the cycle (bring this up, again, later after the TIEE lesson).

Lesson Resources

This Activity is included in: