} CAS: Teachers - A Carbon Molecule's Journey

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Anytime Lesson Plan: A Carbon Molecule's Journey


In this activity students will learn that carbon, and specifically carbon dioxide, moves around in the environment between land, atmosphere and ocean.  They will learn that there is a finite amount of carbon on earth, and that it takes an extremely long time for carbon to create fossil fuels.  As a result, they are considered to be a non-renewable resource.



In this activity students will:
  1. Learn that carbon, and specifically carbon dioxide, moves around in the environment between land, atmosphere and ocean.  Each molecule of CO2 takes a different path.
  2. Learn that there is a finite amount of carbon on earth, and that it takes an extremely long time for carbon to create fossil fuels.  As a result, they are considered to be a non-renewable resource.


  • Carbon dioxide molecule cards (two per student – template provided)
  • Markers (red, blue, green)
  • Carbon Cycle Role-Play Cards (three decks: ocean, land, atmosphere – provided, print 3 copies)
  • Carbon Cycle Region Cards (ocean, land, atmosphere – provided)
  • Individual carbon cycle maps (one per student – template provided)


  • algae: a general term for microscopic or larger aquatic plants. They differ from trees, bushes, and other flowering plants because they lack true roots, stems, and leaves.
  • atmosphere: the mixture of gases surrounding the earth, held in place by gravity
  • biosphere: the parts of the land, sea, and atmosphere in which organisms are able to live
  • carbon: a naturally abundant, nonmetallic element that occurs in all organic compounds and can be found in all known forms of life
  • carbon dioxide: a colorless, odorless gas that is present in the atmosphere, formed during respiration, produced during organic decomposition, used by plants in photosynthesis, and formed when any fuel containing carbon is burned
  • hydrosphere: all of the earth's water, including surface water (water in oceans, lakes, and rivers), groundwater (water in soil and beneath the earth's surface), snow cover, ice, and water in the atmosphere, including water vapor
  • lithosphere: rigid, rocky outer layer of the earth
  • photosynthesis: the process by which green plants, algae, diatoms, and certain forms of bacteria make carbohydrates from carbon dioxide and water, using energy captured from sunlight
  • respiration: processes that take place in the cells and tissues during which energy is released and carbon dioxide is produced



  1. Print and cut out enough CO2 molecule cards for everyone in the class. Each student will receive 2 copies, one for each round of play.
  2. Print 4 copies of the role-play card decks. Make sure that they are double-sided.
  3. Designate a large open space for this activity. If working outside, use chalk to designate a large rectangular area. Then, use chalk to divide the space into three regions, one for the ocean, one for the land, and one for the atmosphere as shown below. Another option is to draw a picture on the board of the three regions shown below and then designate different areas of the classroom to represent the ocean, the land, and the atmosphere. Place the appropriate Carbon Cycle Region card in each area.


Carbon is a common element on earth and can be found in plants, animals, rocks, the atmosphere and ocean. Carbon dioxide (CO2) is one form that carbon can take as it moves through the carbon cycle.  CO2 is produced naturally by living things when they breathe (respiration) and used by plants and algae during photosynthesis.  Natural events like wildfires and volcanoes also release large amounts of carbon dioxide.  In modern times, humans have developed many processes and machines which burn fossil fuels and also release CO2.  

  1. Have students recall some of the things in their daily lives that produce CO2 (encourage them to think of both natural and human-made sources).  Make a list of these items on the board.
  2. Then discuss how the carbon contained in any one thing doesn’t stay there forever. Carbon atoms move from one thing to another in what is called the carbon cycle. Parts of the carbon cycle happen very quickly, like when plants take in carbon dioxide from the atmosphere for photosynthesis. But, other parts of the carbon cycle happen very slowly. Tell students that in this activity, they will learn how carbon dioxide moves from one place to another, by performing a carbon cycle role-play.


  1. Divide the students into three sources (groups): ocean, land and atmosphere. Ask students to write their “source” on their CO2 molecule card.
  2. Set out the Carbon Cycle playing cards (24 per region) and region card at the appropriate regions (ocean, land and atmosphere).  You can use a desk or table to be the central point of each region and place the sign at the table.  Set the appropriate colored marker at each region (ocean – blue, land – green, atmosphere – red). Do not use the “Human Impact” cards yet.
  3. Ask the students to take their CO2 molecule cards to go to their assigned region.
  4. Students will line up with the front of the line at the stack of cards.
  5. Game play will last for a set amount of time, for example 10 minutes. 
  6. Game play will run concurrently for all students.  For example, students can ‘play’ for 10 minutes.  There is no need to have students in one region to wait for students to pick a card from another region.  In other words, a student in the Land region will be pulling a card at the same time as a student in the Ocean region and they will each follow the direction on their own card.  There will be quite a bit of movement around the room until time runs out.
  7. When a student reaches the front of the line, s/he will take a card off the top of the deck, read it out loud to the rest of the students in line. Tell students that some cards tell students to go to the front of the line. If there is more than one of those students, they should insert themselves in the front of the line behind the other students with the “Front of Line” cards. 
  8. The student will follow the directions on the card and keep the card they picked.  For example, the card might say “GO TO OCEAN: FRONT OF LINE”.  This student will go to the ocean region and cut to the front of the line and immediately pick an ‘ocean’ card.  In another case, the card might say “STAY IN ATMOSPHERE: GO TO END OF LINE”.  This student will move to the back of the line, but stay in the atmosphere region.
  9. Student should take each card they read with them in order to help answer the questions on the worksheet once game play is over.
  10. Before the student moves on, s/he should put a check mark in the box by the next available number on the back of the CO2 molecule’s card.
  11. Each student should make their way through the carbon cycle until the time is up.   At the end of game play, all students will return to their seats regardless of how many times they may or may not have traveled from one region to another.  Each of their cards has space to record 4 individual ‘movements’ from one region to another, but they may have more or less.  In the event that they travel more than 4 times, they should continue to record their movements on their card using the colored pens (step 10).
  12. Once everyone has completed their carbon cycle and is seated, pass out the Individual Carbon Cycle maps to each student. Write the marker color key on the board: red=atmosphere, blue=ocean, green=land.
  13. Tell students that they will use their CO2 molecule cards to help them chart the journey they just experienced on their map.  They should label the region they started in with “START”. Then they should draw arrows to the places that they went and write the numbers of their visits (from their cards) to the other regions.
  14. Ask students to tally up how many times they stopped at each region.  Then graph the class’s ending results (total number of times students visited each region) and write down any observations the students make.
  15. Students will use the cards they collected at each of the locations visited to answer the remaining questions on the worksheet.  
  16. You may want to allow some time at the end for students to share their maps with the group or have a class discussion about the questions.
  17. Once the questions have been answered, mix the “Human Impact Cards” in with the Land deck and play the game again.   Pass out new CO2 molecule cards to each student.  Repeat steps 3-16, graphing the round 2 results and filling out the 2nd side of the worksheet at the end of game play.


Begin by asking questions such as the following:

  • What was it like to have to wait for your turn to cycle?
  • How did the carbon cycle change when human impacts were added?
  • Does anyone know why human impacts changed the cycle?
Burning fossil fuels takes carbon from sediments and rocks where fossil fuels are buried and puts it into the atmosphere.  This is because fossil fuels release carbon-containing gases when they are burned. Cutting and burning trees takes carbon from the land plants and puts it into the atmosphere because when trees are burned, the carbon that was stored in their structures is released as carbon-containing gases. Humans have not created more carbon on earth, but we move carbon from one place to another more quickly than would naturally happen and this affects the climate of the planet.


  • Mackenzie, F.T. (2003). Our Changing Planet:  An Introduction to Earth Science and Global Environmental Change. Upper Saddle River, NJ: Prentice Hall.
  • NASA, earth observatory. The carbon cycle. Retrieved on January 14, 2008 from http://earthobservatory.nasa.gov/Library/CarbonCycle/carbon_cycle2.html
  • Tarbuck, E.J., & Lutgens, F.K. (2002). Earth: An Introduction to Physical Geology.  Upper Saddle River, NJ: Prentice Hall.    


California Content Standards

Grade Three

Physical Sciences

  • 1a. Students know energy comes from the Sun to Earth in the form of light

Life Sciences

  • 3c. Students know living things cause changes in the environment in which they live:  some of these changes are detrimental to the organism and some are beneficial

Grade Four

Life Sciences

  • 2c. Students know decomposers, including many fungi, insects, and microorganisms, recycle matter from dead plants and animals

Earth Sciences

  • 5a. Students know some changes in the earth are due to slow processes, such as erosion, and some changes are due to rapid processes, such as landslides, volcanic eruptions, and earthquakes.

Grade Five

Physical Sciences

  • 1a. Students know that during chemical reactions the atoms in the reactants rearrange to form products with different properties.
  • 1b. Students know all matter is made of atoms, which may combine to form molecules.
  • 1g. Students know properties of solid, liquid, and gaseous substances, such as sugar (C6HO6), water (H2O), helium (He), oxygen (O2), nitrogen (N2), and carbon dioxide (CO2).
  • 1h. Students know living organisms and most materials are composed of just a few elements.

Life Sciences

  • 2f. Students know plants use carbon dioxide (CO2) and energy from sunlight to build molecules of sugar and release oxygen.
  • 2g. Students know plant and animal cells break down sugar to obtain energy, a process resulting in carbon dioxide (CO2) and water (respiration).

Grade Six

Life Sciences

  • 5a. Students know energy entering ecosystems as sunlight is transferred by producers into chemical energy through photosynthesis and then from organism to organism through food webs.
  • 5b. Students know that matter is transferred over time from one organism to others in the food web and between organisms and the physical environment.

Grade Eight

Life Sciences

  • 6a. Students know carbon, because of its ability to combine in many ways with itself and other elements, has a central role in the chemistry of living organisms.
  • 6b. Students know that living organisms are made of molecules consisting largely of carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur.


Next Generation Science Standards

Grade Four

Performance Expectation

5-ESS2-1 Develop a model using an example to describe ways the geosphere, biosphere, hydrosphere, and/or atmosphere interact.


ESS2.A Earth Materials and Systems 

Middle School

Performance Expectation

MS-LS2-3 Develop a model to describe the cycling of matter and flow of energy among living and nonliving parts of an ecosystem.

MS-ESS2-1 Develop a model to describe the cycling of Earth’s materials and the flow of energy that drives this process.


LS2.B Cycle of Matter and Energy Transfer in Ecosystems

ESS2.A Earth’s Materials and Systems


Scientific Knowledge Assumes an Order and Consistency in Natural Systems



Carbon is an extremely common element on earth and can be found in all four major spheres of the planet: biosphere (plants and animals), atmosphere (sky), hydrosphere (water), and lithosphere (earth). Carbon is found in both the living and non-living parts of the planet, as a component in organisms, atmospheric gases, water, and rocks. The carbon contained in any of the planet’s spheres does not remain there forever. Instead, it moves from one sphere to another in an ongoing process known as the carbon cycle. The carbon cycle is extremely important on earth as it influences crucial life processes such as photosynthesis and respiration, contributes to fossil fuel formation, and impacts the earth’s climate.

Besides the relatively small additions of carbon from meteorites, the amount of carbon on the planet is stable. However, the amount of carbon in any given sphere of the planet can increase or decrease depending on the fluctuations of the carbon cycle. The cycle can be thought of in terms of reservoirs (places where carbon is stored) and flows (the movement between reservoirs). The atmosphere, the biosphere, the hydrosphere, and the lithosphere are the reservoirs and the processes by which carbon moves from one reservoir to another are the flows. Although carbon is extremely common on earth, pure carbon is not common. Rather, carbon is usually bound to other elements in compounds. Thus, when carbon moves or cycles, it is usually doing so within compounds, such as carbon dioxide and methane. 

The many processes that move carbon from one place to another happen on different time scales. Some of them happen on short time scales, such as photosynthesis, which moves carbon from the atmosphere into the biosphere as plants extract carbon dioxide from the atmosphere. Some carbon cycle processes happen over much longer time scales. For example, in the ocean, organisms with calcium carbonate skeletons and shells die and some of their remains, those that don’t decompose, sink towards the ocean floor. Upon reaching the ocean floor, the carbon that was stored in their bodies becomes part of the carbon-rich sediment and is eventually carried along, via plate tectonic movement, to subduction zones where it is converted into metamorphic rock. These two examples show the extreme variety of processes that take place in the carbon cycle.

In general, the short-term carbon cycle encompasses photosynthesis, respiration, and predator-prey transfer of carbon. On land, there is a flow of carbon from the atmosphere to plants with photosynthesis and then a flow back to the atmosphere with plant and animal respiration and decomposition. For aquatic plants, photosynthesis involves taking carbon dioxide dissolved in the water around them and respiration and decomposition put carbon dioxide back into the water. In addition to moving between plants and the atmosphere or the water, carbon dioxide is also constantly moving between the atmosphere and water via diffusion. The long-term carbon cycle encompasses more of the lithospheric processes. It involves the weathering and erosion of carbon-containing rocks, the accumulation of carbon-rich plant and animal material in sediments, and the slow movement of those sediments through the rock cycle. 

There are natural fluctuations in the carbon cycle, but humans have been changing the carbon flows on earth at an unnatural rate. The major human-induced changes result in increased carbon dioxide in the atmosphere. The largest source of this change is burning fossil fuels, but other actions such as deforestation and cement manufacturing also contribute to this change in the carbon cycle. Because carbon dioxide and methane are greenhouse gases that help to control the temperature of the planet, the human-induced increase in atmospheric carbon levels is resulting in a host of climatic changes on our planet. As discussed above, the natural carbon cycle is important to learn because it is crucial to many of earth’s processes, but an understanding of the carbon cycle is especially important at this time in human history because of the dramatic and consequential alterations we are making to the cycle.

The entire carbon cycle is composed of even more specific flows between the atmosphere, biosphere, hydrosphere, and lithosphere than those discussed here. This role-play teaches an age-appropriate version of the carbon cycle. Although there are more specific details involved in the earth’s complicated carbon cycle, this version will highlight some of the most important components and will teach students the overall concept that carbon is finite and moves through the different spheres of the planet. Before teaching the Carbon Cycle Role-Play, read through the table in the procedure section to get a better understanding of the specific flows your students will be learning. For more detailed carbon cycle information investigate the resources and references listed at the end of the lesson plan.

Example of Ways Carbon Can Cycle

carbon cycle diagram


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