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You are going to have the chance to use the scientific method and experiment with how you can use light as a variable to determine its affect on the growth of plant seeds. Make sure that you use clear containers so that you can observe the seeds germinating. Remember to control all other variables so you are only testing the affect of light!
 

Materials

  • Seeds - any kind - wheat seeds from a health food store usually germinate in a day or two
  • Potting soil
  • Two empty 35mm. film canisters
  • Metric ruler
  • Water
  • Pipets
  • Aluminum foil
  • Paper towel or cotton cloth
 
Safety concerns Be sure to keep all chemical safety rules. As with all science lab activities, the most important safety rule is to follow all teacher directions.

Procedure:

  1. Begin by creating a small hole (<6mm) in the center of your canister. You may carefully heat a nail over a bunson burner. Other options include using a soldering iron or a drill.
  2. Always begin a planting cycle on a Monday or Tuesday. This allows at least three consecutive school days for observations.
    • If you do this in a school that is on the block schedule, you will need to make observations on days that you normally do not attend class.
  3. Moisten the potting mix until it is slightly damp.
  4. Insert a wick of paper towel or small piece of cotton cloth through the small hole in the bottom of the canister.
  5. Fill the film canister half full with potting mix.
  6. Put four seeds around the perimeter of the film canister. You should be able to see the seeds from the outside.
  7. Add more potting mix until the film canister is three-fourths full. Do not pack the soil.
  8. Tear off two pieces of aluminum foil.
  9. Fold the edges of each piece of aluminum foil to form a "tray" to put under your canister.
  10. Put one film canister in a well-lit place (such as a window ledge) and the second film canister in a dark place (such as inside a cabinet.)
  11. If the soil feels dry, add water with a pipette or eyedropper. Once the plant germinates be careful not to over water.
  12. Take observations each day for about two weeks. Your observations could include: days to germination, plant or leaf color, mold, shape of plant or leaf, etc.
  13. When your plants are high enough, measure each plant in centimeters and take an average for each of your two test locations.
  14. Record your data similar to the table below:
      Seeds in the dark Seeds in the light
    Monday    
    Tuesday    
    Wednesday    
    Thursday    
    Friday    
    Monday    
    Tuesday    
    Wednesday    
    Thursday    
    Friday    
  15. Use the data to create a line graph to compare the variable of light on seed germination and plant growth.
 

Analysis:

  1. Which location had seeds which germinated first?
    • Was this what you expected?
    • Why or why not?
  2. At which location were the tallest plants produced?
  3. Is light a necessary factor for seed germination?
    • Defend your answer using the data from your experiment.
  4. How is light a factor for plant growth?
 
Extension:
Do a similar experiment using different variables such as fertilizer versus water, sand versus potting soil, or another variable. Make sure you get permission from an adult to do so.

Review Science safetey rules here.

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  1. The title of the activity
  2. The URL (Internet address)
  3. Your name.

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Teachers should view the Teacher Site Map to relate Sci-ber text and the USOE 8th grade science core.


Updated October 24, 2008 by: Glen Westbroek

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