This is a 4-5 day unit on the carbon cycle and the effects of human perturbations to it. The unit consists of four lessons each of which has an associated homework assignment. Topics covered include the carbon cycle, the greenhouse effect, and ocean acidification.

Carbon Cycle:
  • There are 4 large reservoirs of carbon on Earth (Atmosphere, Hydrosphere, Lithosphere, and Biosphere).
  • The different forms carbon takes within these reservoirs.
  • The processes that transform carbon (photosynthesis, respiration, carbonate secretion, combustion, carbonate weathering/carbonic acid-bicarbonate-carbonate reactions, gas solubility, burial) and rules governing them.
  • The relative sizes of these reservoirs, and fluxes in/out of them.
  • Breaking chemical bonds releases energy. Forming chemical bonds requires energy.
  • Understand the origin and composition of the different fossil fuel reservoirs.
Greenhouse Effect:
  • CO2 and other greenhouse gases (GHGs) trap heat by absorbing IR radiation.
  • For the global energy budget, ins must equal outs. If not, something must change.
  • How many gigatons = 1 ppm.
  • How many ppm of CO2 were in the atmosphere before the industrial revolution, and how many there are now.
  • The greenhouse potential of different GHGs.
  • The Earth has had no ice sheets, and it has had ice sheets everywhere.
  • How we know CO2 is rising.
  • Where we get our CO2 numbers from.
Ocean Acidification/Carbonate Chemistry Titration:
  • The ability to write and understand the chemical equations governing carbonate chemistry.
  • Understanding that the true threat of ocean acidification is NOT the acid itself but the reduction it causes in carbonate ion concentration.
  • An understanding of what pH is and how it is buffered in the ocean by carbonate chemistry.
  • The broader ecological implications of ocean acidification.
  • The ability to do a titration, and understand what it accomplishes.
  • The role of a buffer.
Carbon Cycle:
  • Fossil fuels come from dinosaurs.
  • All carbon released into the atmosphere is bad.
  • Trees don't respire, they only photosynthesize.
  • Only living things participate in/are important for the carbon cycle.
  • On a chemical level, respiration and burning are different.
  • The atmosphere is the biggest carbon sink.
  • Shells are part of the biosphere (they are part of the lithosphere).
  • All organic matter in the soil is part of the lithosphere.
Greenhouse Effect:
  • CO2 is not a greenhouse gas.
  • Excess atmospheric CO2 is good for plants.
  • Atmospheric concentrations of greenhouse gases have always been constant.
  • There has always been ice on Antarctica.
  • The climate has always been pretty similar to today.
  • Climate change isn't real, or isn't serious.
  • We're not responsible for climate change.
Ocean Acidification/Carbonate Chemistry Titration:
  • The ocean needs to be acidic to have a negative effect on ocean life.
  • Ocean acidification is the main cause for coral's demise.
  • Ocean acidification is hurting the organic parts of critters.
  • Ocean acidification is caused by us dumping stuff into the ocean.
  • The overview of the entire unit as well as background documents for the three components of this unit are available here as well as below in the Daily Activities panel.
  • Day 1: Carbon cycle reservoirs, mechanisms, fluxes, activity and story.
  • Day 2: Greenhouse effect lecture and worksheet.
  • Day 3: Ocean acidification lab and worksheet.
  • Day 4: Carbonate Chemistry titration lab and worksheet.
  • Day 5: Carbonate Chemistry and Titration finale.
  • This unit was developed for and taught to an 11th-grade International Baccalaureate Biology class. The lessons took place over 4 full 90-minute class periods and the first 10 minutes of a 5th day. About 100 students received the original lessons, though pieces of it have been taken and applied to other student groups in both formal and informal settings. Some students had taken chemistry.
  • Carbon cycle assessment was for students to write a story. In this story, they would have to tell how a carbon atom was moved between all 4 reservoirs on earth. Creativity was encouraged.
  • Greenhouse effect assessment was a worksheet.
  • Ocean acidification assessment was a worksheet to be filled out in conjunction with a lab.
  • Assessment for the Carbonate Chemistry titration lab was for students to write up results and conclusions for the lab. This lab was in accordance with IB guidelines on lab write-ups.
  • The day began with a brief chat trying to get students to think about all the things are made of carbon, and how you go from dinosaur dung to delicious ice cream with the same basic parts. This served as a “hook”, and was followed by a “field trip” out to the parking lot. One of the instructors has a car that runs on biodiesel converted from vegetable oil, and he there poured some of the biodiesel into his car. This stoked the students' imaginations further, and got them thinking about the difference between different fuels. This was followed by a 10-minute lecture on the 4 main reservoirs of carbon, and the 8 processes that move carbon between those reservoirs. A jacob's ladder was made to emphasize that repiration/combustion and photosynthesis are the exact same reaction in different directions. This was followed by a kinesthetic activity which further explored the carbon cycle as well as the concept of flux. Students were then asked to write a creative story of how a carbon atom could move from one carbon reservoir to the others, with the requirement that the student include all 4 reservoirs in their story.
  • This day began with a college style lecture. The lecture was actually given at the University of California San Diego for a non-majors Earth Science class titled “Earth History and Evolution”. The lecture involved a kinesthetic demonstration of how the greenhouse effect works using 3 student volunteers, and was followed by a worksheet, which if not completed in class was homework.
  • This day began with a lecture on carbonate chemistry in the ocean, the role of atmospheric CO2 in this chemistry, and how this might affect carbonate-secreting organisms in the ocean. As the threat to organisms from ocean acidification arises more from under saturation of the carbonate ion in seawater than from an actual increase in acidity, this point was emphasized. The students then completed a lab using vinegar and deionized water with chalk to emphasize the point that under saturation can be as damaging to calcium carbonate secreting organisms as acidic conditions. The students turned in the lab worksheet for homework.
  • Instructors were only able to provide clarifying questions for this lab. Students dissolved a shell in vinegar, and titrated 0.1 M HCl into the vinegar to return the solution to it's original pH. Students then used the volume of HCl added to calculate how many moles of calcium carbonate were dissolved into solution.
  • Students weighed their dried shells for a final data point. They then had all the information they needed to complete the lab.

Reflection and Absorbtion

Ice Sheet

Kinetic Energy
Lesson Specifics
  • Grade Level: This unit was developed for and taught to an 11th-grade International Baccalaureate Biology class.
  • Time Frame: 4 full 90-minute class periods and the first 10 minutes of a 5th day.
  • US Science Standard - IB topic 5.2.2 and 5.2.3: "Historical record of atmospheric gases and atmospheric gases and the enhanced greenhouse effect."
  • US Science Standard - Earth Sciences 4a: "The relative amount of incoming solar energy compared with Earth’s internal energy and the energy used by society."
  • US Science Standard - Earth Sciences 4b: "The fate of incoming solar radiation in terms of reflection, absorption, and photosynthesis."
  • US Science Standard - Earth Sciences 4c: "The different atmospheric gases that absorb the Earth's thermal radiation and the mechanism and significance of the greenhouse effect."
  • California Standard - Earth Sciences 7b: "Global carbon cycle: the different physical and chemical forms of carbon in the atmosphere, oceans, biomass, fossil fuels, and the movement of carbon among these reservoirs."
  • California Standard - Biology 6d: "How water, carbon, and nitrogen cycle between abiotic resources and organic matter in the ecosystem and how oxygen cycles through photosynthesis and respiration."
  • California Standard - Biology 6e: "A vital part of an ecosystem is the stability of its producers and decomposers."
  • California Standard - Chemistry 5d: "How to use the pH scale to characterize acid and base solutions."
  • California Standard - Chemistry 5g: "Buffers stabilize pH in acid-base reactions."

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