[WW HOME][CLIMATE CHANGE][GREENHOUSE GASES][SEARCH]

Plants and the Carbon Cycle

Teacher Page

Hypothesis:  
Plants reduce the amount of carbon dioxide in the atmosphere.
Materials per student group:
  • 2 large mayonnaise jars (large jars with a wide mouth lid)
  • soil
  • plants
  • CBL with carbon dioxide probe (or other carbon dioxide measuring device)

    •  
      Procedure:
    1. Place moist soil in both jars.
    2. Put the plants in one jar (this is the experimental jar)

      3. * Make sure soil is moist before placing plants in jar.  Some adjustment may be necessary for large plants (see photo).
    3. Measure the carbon dioxide in this jar and seal the lid of the jar.
    4. In the second jar, measure the carbon dioxide and seal the lid of the jar. (This is the control jar)
    5. Record the carbon dioxide measurements in the space provided in ppm.

      6. Experimental jar-  _________________ppm
      Control jar-  _____________________ppm 
    6. Place jars in sunlight and let sit for three to five days.

      7. Monitor the health of the plants making sure they don't get too hot.
    7. After this time period,  record your observations of the two jars. 

      8. Students may observe that the plants have grown, have turned brown,  or that condensation has taken place.
    8. Remove the lids of both jars and take another carbon dioxide measurement in each jar.
    9. Record your measurements in the space provided.

      10. Experimental jar-  _____________ppm
      Control jar -  _________________ppm
    10. Calculate the difference in ppm for experimental and control jars.

      11. In the trial we did, the carbon dioxide reading for the experimental bottle decreased by 2/3 after 3 days. However, the carbon dioxide readings were also reduced by 1/3 in the control bottle; this decrease may be caused by soil or water absorbing some carbon dioxide. Students results will vary.
      Experimental jar ppm difference- ________________ ppm
      Control jar ppm difference- ____________________ ppm
    11. Combine class data and calculate the median for each jar.

      12. Teacher should construct a data table on the board in which students'  results are written.  As a math extension, have students construct a bar graph  or box plot and   have  students calculate mean, mode, and range.
    12. Experimental jar median- ________________ppm
    13. Control jar median - ____________________ppm
    Conclusion:
    Did your observations support your hypothesis? Defend your answer.
    Students should draw conclusions that match their data but are likely to observe a decrease in carbon dioxide. Plants take in carbon dioxide during photosynthesis and release oxygen. Some of the carbon dioxide is stored in the plant and some of it is released back to the air during plant respiration. Follow up:
    On a separate page name one variable in this experiment that you could investigate in a follow up experiment. Describe how you could carry out this experiment.
    Variables may include types of plants, size of plants, number of plants, size of jar, amount of sunlight, length of experiment.  Allow students to do their own investigation.  The assessment rubric is used to grade the follow up for student understanding.
     
    < Back to Greenhouse Gases Home Page  /  Background Information / Activities Page  / Resources Page / Student Page >
     
     
     

     
     
     

    [WW HOME][CLIMATE CHANGE][GREENHOUSE GASES][SEARCH][FEEDBACK]

    Woodrow Wilson Leadership Program in Environmental Science * lpt@www.woodrow.org
    The Woodrow Wilson National Fellowship Foundation * webmaster@woodrow.org
    CN 5281, Princeton NJ 08543-5281 * Tel:(609)452-7007 * Fax:(609)452-0066