Module D. Pollution

(Level of difficulty ***)

Question: How do chemicals and pollutants in the environment affect plant health?

Materials you will need:
•2 or more empty rinsed plastic yogurt containers or single-use cups (any size)
•Water (tap water is fine)
•Leaves or flowers of indoor or outdoor plants
•Household chemicals, such as salt, sugar, baking soda, vinegar, laundry detergent, dish soap, Windex, etc.
•A measuring cup or spoon

•Using scissors, carefully cut 3 or more green leaves or fresh flowers from a plant
•Prepare your chemicals by mixing them with water (see below for mixing suggestions)
•Place one leaf or flower in a cup filled with water
•Place the second leaf or flower in cup filled with the chemical of choice
•Put the cups with leaves/flowers in a bright sunny place (a windowsill)
•Observe what happens to the plant parts over time

Helpful hints and suggestions:
•When you collect leaves or flowers, it is a good idea to cut them with a stalk (have an adult help you if you are unsure)
•You may want to put multiple leaves or flowers in the same cup
•Don’t forget to label the containers (for example, “water”, “salt”, “soap”, and so on), so after your experiment is done you will not get confused which pot is which.
•You can compare the effect of several different chemicals on plant health (do not forget to include water only as your control!), or test different amounts (concentrations) of a single chemical.
•Some plant varieties are more sensitive to certain chemicals than others and some chemicals are more harmful to plants than others, but as a general guideline, try adding 1 teaspoon of the chemical to each 5 ounces of water (have an adult help you with the measurements).

Expected results:
•Leaves and flowers kept in cups with added chemicals typically would get sick and die earlier than leaves and flowers placed in clean water. The health of the plants depends on which chemical and how much of it you used, and on how long you kept the plants in that chemical.
•Some chemicals, such as sugar, will not harm the plants

Follow-up questions:
•Why do you think chemicals affect plant growth?
•Do you think all chemicals are bad for the plants or some are good?
•What can you and your family do to reduce amount of chemicals dumped into environment?
•If you were to repeat the experiment, would you get the same results?
•Do you think the results of your experiment would be different if you used a different amount (concentration) of the same chemical or switched to another chemical?
•Do you know the type of plant (the species) you did your experiment on?
•Would the outcome of the experiment be different if you used leaves of another type of plant or tree variety?