Bubbling Plants

This lesson plan provides everything a teacher needs to have students set up experiments using Elodea plants and varying degrees of light to test their effect on photosynthesis. This lesson plan walks students through the process of photosynthesis using Elodea plants and varying degrees of light.

Weblink address (URL): 
Bubbling Plants

Standards & Objectives

Learning objectives: 

After this activity, students should be able to:

  • Explain that photosynthesis is a process that plants use to convert light energy into glucose, a source of stored chemical energy for the plant.
  • Describe photosynthesis as a set of chemical reactions in which the plant uses carbon dioxide and water to form glucose and oxygen.
  • Describe a simple experiment that provides indirect evidence that photosynthesis is occurring.
  • Describe the effects of varying light intensity on the amount of photosynthesis that occurs.

Lesson Variations

Blooms taxonomy level: 
Applying
Extension suggestions: 
  • The light that comes from the sun consists of light waves of many different wavelengths. In the visible spectrum of light, these range from red with the longest wavelength, to violet with the shortest wavelength. Chlorophyll does not respond equally to all wavelengths, or colors of light. Have students use the same experimental setup to determine what color or colors of light result in the most photosynthetic activity. The only modification they need to make is to loosely cover the beaker with colored plastic wrap or cellophane during the five minutes of bubble counting. Since blue wavelengths are the best for most plants, be sure that this is one of the colors available. If possible, have red and one other color available as well.

Helpful Hints

Materials List

  • 5 liters (about 1¼ gallons) of aged tap water (tap water in an open container that has been allowed to sit for 36-48 hours to eliminate the chlorine used in municipal water supplies)
  • 15-20 total Elodea plants; these are hardy freshwater aquarium plants sold in bunches at pet stores and suppliers such as Carolina Biological Supply Company (www.carolina.com)
  • string, yarn or twist ties for tying Elodea plants into bunches
  • small rocks or similar objects to serve as weights to hold the Elodea plants underwater
  • 500-ml beakers, 1 per team
  • baking soda, a few tablespoons (sodium bicarbonate)
  • timers or watches with second hands, 1 per team
  • small adjustable desk lamps that can be set up so that their light bulbs are a few inches above the beakers and shine vertically down onto them; flashlights with strong beams that are mounted on ring stands also work; 1 light source per team

References

Contributors: 
Karla Fultz
Originator: 
Ayers Institute for Learning & Innovation