Carbon and Nitrogen Cycles (1 of 2)

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Students will be able to describe how carbon and nitrogen cycle through ecosystems.

Big Idea

Matter is constantly cycled between living and nonliving parts of the environment.


5 minutes

To start us off, I tell students: "The water you drink every day has probably passed through at least one other person’s body. At your tables discuss how this could happen safely." I make it a point to clarify that they are to take on the persona of a water molecule, and talk about how that water molecule could safely pass on from one organism to the next. I pointedly state, "No one is drinking anyone's urine."

Note to teachers: Often students look at me like I'm crazy when I ask them to do this, so I display a diagram of the water cycle. 

This is enough to initiate the conversation between the students, and works well to activate their prior knowledge.

I allow students to talk at their tables for a couple of minutes, and then I tell the students that we will go around the classroom using a verbal chain-note. Each table will have to add a statement that includes, "I (the water molecule) _______ and go to _______. Then what happens? - Table __"

I start it off: "I am am a water molecule that was drunk by _____ . I am transpired and evaporated from the surface of the skin. I go to clouds. Then what happens? - Table 1". We continue this way until each table has had an a to add to our water cycle.

Once we are done, I tell the students that today we will learn about other elements that are also naturally recycled from living things to non-living things and back again.

Note to teachers: If you have a great relationship with your students the organism that drank you can be a student in the classroom. This brings about a lot of giggles, and definitely increases engagement. However, if you are unsure about how this will be taken by your students, just substitute any other name or an animal. 


10 minutes

I edited the Biogeochemical cycling video by Bozeman Science, embedding it here to provide a very brief overview of the cycling of carbon, nitrogen and phosphorus. 

I decided to show just a portion of the video so students would not get overwhelmed with information. The big idea that I want students to take away is that matter is cycled between living and non-living things because there is a finite amount of the materials needed for life available in our planet.

Traveling Through the Cycles

30 minutes

I tell the students they will now become nitrogen or carbon atoms to play a game similar to the rock cycle game they played a while back.  

I explain that tables will be randomly assigned to one cycle, and that they will need to be very detailed in their work and information they collect since tomorrow they have to explain their assigned cycle to another student.

I randomly assign table groups to one of the cycles. Ideally, I want an even number of students working on each cycle and no more than 4 per table (so that the game can proceed quickly). I explain how to play the game.

Once the explanation is done and students have asked any clarifying questions, I have them pick up the dice, markers and student handouts (carbon cycle game student handoutnitrogen cycle game student handout). As students are playing and gathering their information, they are involved in constructing conceptual models (SP2) that illustrate the cycling of matter through ecosystems. This addresses two Crosscutting Concepts: 

Energy and Matter

  • Matter is conserved because atoms are conserved in physical and chemical processes.

Systems and System Models

  • Models can be used to represent systems and their interactions - such as inputs, processes and outputs - and energy, matter, and information flows within systems.

Note to teachers: The paper size I used to make the game boards (carbon cycle gamenitrogen cycle game) is 13"x19", so you will not be able to print them in regular printers. The best solution is to make a copy of the pdf files onto a flash drive and take them to your local copy shop. I had them printed in 22" x 28", which I believe is big enough. Since it is a black and white print, the cost remains reasonable. It is also worth noting that although students were asked to write down the pathways directly on their "cycles" (CC 1NC 1), many opted to draw and identify the lines, but wrote down the process in the back of the sheet (CC 2NC 2).


5 minutes

To close this lesson, I remind students that they might not be working off their own data tomorrow, so they must give their work to a "reviewer"/elbow partner. The "reviewer" needs to look it over verifying completion (10 turns), with turn numbers and legible explanations. The reviewer will need to provide feedback to the original student, who must then act on the suggestions. Once the reviewer is satisfied, he/she should sign it and turn it in.

This peer review is done to help with accountability, and to ensure that every student will have enough information to explain their cycle the next day. Watch as a student explains the process.