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Projects for Kids About Photosynthesis

Photosynthesis is a process carried out by plants and algae to generate food. Photosynthesis occurs within sub-cellular structures called chloroplasts, which contain a light harvesting molecule known as chlorophyll. In the photosynthetic process carbon dioxide, water and light generate food (sugar molecules such as glucose) and oxygen. Photosynthesis is typically taught in high school science and the format of teaching is often through experiment. There are many simple projects that can be carried out on photosynthesis, and these experiments help the student understand the basics of plant biology.

Effect of Light on Photosynthesis
- Test the effect of light on photosynthesis using a simple pondweed plant. Place pondweed into a large beaker full of water so it stands upright. Put a desk lamp next to the beaker, and orient the light towards the pondweed. Switch on the lamp. After a few minutes bubbles should start appearing on the pondweed leaves and float up to the surface. These are carbon dioxide bubbles generated by photosynthesis. Switch off the light. The bubbles should stop after a few minutes. This simple project demonstrates that light is needed for photosynthesis.
Effect of Light Color on Photosynthesis
- Place pondweed in a large beaker with water and place a desk lamp next to the beaker. Place a number of colored filters over the lamp to see the effect on photosynthesis. The light harvesting molecule chlorophyll only uses certain wavelengths, or colors, of light to carry out photosynthesis. Use red, blue and green filters. The student will find that the red and blue filtered light still produces large amounts of photosynthesis while green filtered light produces very little. Evidence of photosynthesis is found by looking for carbon dioxide bubbles.
Effect of Temperature on Photosynthesis
- Place a large beaker of pondweed on a hot plate. Place a desk lamp next to the beaker. Photosynthesis is carried out by biological catalysts known as enzymes. Enzymes are only able to function within certain temperature limits. This experiment allows the student to determine the temperature range over which photosynthetic enzymes function. The number of carbon dioxide bubbles produced by the pondweed is counted for one minute. Repeat for a range of temperatures between 68 degrees Fahrenheit and 140 degrees Fahrenheit.
Effect of Light Intensity on Photosynthesis
- Pondweed is placed in a beaker full of water and a variable intensity lamp is placed next to it. The number of bubbles produced from photosynthesis is counted as a function of the lamp intensity. Photosynthesis is should increase with light intensity. This experiment can also be used with colored filters to see if a certain color requires less light to reach a threshold number of bubbles.

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