A Demonstration of Photosynthesis and Transpiration

Suggested Grades



Students will examine the effect that light and air has on green plants.


  • two planting containers
  • seeds (lima beans, peas, broad beans…)
  • soil
  • a dark area and a bright area
  • a glass bottle or jar


  • Give the seeds a little head start by soaking them in water overnight.
  • With the class, plant a few seeds in each container.
  • Place one container in a dark place and the other in a bright place.
  • Ask students to predict and record (drawing and/or writing) what they believe will happen to the seeds above and below the soil.
  • Keep the seeds in their places for a little over a week, watering them when the soil gets dry.
  • After this time, remove the seed from the dark place and compare it to the one placed in the bright place. Ask students to record what they see. Were their predictions correct?
  • Separate one seedling away from each container compare the root systems. Ask students to record what they see. Were their predictions correct?
  • Have a class discussion on reasons the difference happened. Explain photosynthesis (Simple definition: plants using light to make food for itself).
  • Place the rest of the unhealthy seedlings in the bright place, record any changes. Explain photosynthesis.
  • Place the healthy seedlings in bright place with a clear bottle or jar on top of them.
  • Overnight, condensation will collect on the inside of the bottle or jar. This is the water vapor that is emitted by the plant when it exchanges oxygen for carbon dioxide, which is transpiration