Photosynthesis Lab – How Light Color Affects Growth


This investigation was designed for 9th grade biology for a unit covering plants and photosynthesis. Students choose the type of plant: radish, spinach, or lettuce.

They can switch the color of light to different colors, such as green or violet. Plants are then shown fully grown and students drag a ruler to measure the height in centimeters.

The investigation is completed using a simulator at MHE which eliminates the need to grow real plants. If time permits, you can grow radish seeds fairly quickly and use colored cellophane to show kids a “real-world” experiment. This is a favorite for science fair projects!

AP Biology classes have a more advanced inquiry lab using leaf disks cut from spinach. In this investigation, students also examine the role of carbon and light intensity.

If you are looking for virtual lab that explores light intensity, check out the OLABS virtual simulator and this student worksheet that goes with it.

Grade Level:  8-10 | Time Required:  ~50 minutes

HS-LS1-5 Use a model to illustrate how photosynthesis transforms light energy into stored chemical energy.

*Revised 2022