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Do Plants Need Light?

Author(s): Nancy Moreno, PhD, and Barbara Tharp, MS.

Let's Talk About It

In this activity, students conducted an experiment with bean plants grown in the classroom, through which they discovered that light is necessary for healthy plant growth. Have students complete the remaining questions on the “Just Growing Up” sheet. Then, discuss students’ results as a class. Students should be able to conclude that any observed differences between the two groups of plants resulted from the difference in available light. 

Ask, Were the plants all about the same size before you moved pots 3 and 4 out of the bright light? Are all the plants still the same size? Why do you think that is so? Are there any differences other than size? Help students to conclude that differences in growth (plants with less light will have grown less or will have developed tall, narrow stems) and color (the plants with less light will be lighter green) were caused by the differences in the availability of light. 

Ask, What is the only thing that was different about the two sets of pots? (Only the amount of light changed; all other aspects of the experiment—water, soil, seedlings, pots, planting method—were unchanged for both groups.) Ask, Where do you think the plants in pots 1 and 2 got the materials and energy to produce more stems and leaves? What were the plants in pots 3 and 4 missing? What do you think would happen if we put the plants in pots 3 and 4 back in the light? 

Funded by the following grant(s)

National Institute of Environmental Health Sciences, NIH

National Institute of Environmental Health Sciences, NIH

My Health My World: National Dissemination
Grant Number: 5R25ES009259
The Environment as a Context for Opportunities in Schools
Grant Number: 5R25ES010698, R25ES06932