Can you use gray water (water that has been used for bathing or washing) to water your plants? Does it matter what type of soap you used for your cleaning? Are some plants more tolerant of gray water than others?
How does the presence of soap or detergent in water affect plant growth? seed germination?
What effect does the presence of phosphates have, if any, on the oxygen level of water in a pond?
Does the pH of rain or other precipitation (snow) vary according to season?
Is the pH of rain the same as the pH of soil?
What organisms can you use as indicator organisms to alert you to a dangerous environmental condition in the environment?
How does an oil spill affect marine life?
Are carbon filters as effective with chlorinated or fluoridated water as they are with water that does not contain chlorine or fluoride?
Can you use a plant to gauge the level of air pollution?
Can you use plants to remove air pollutants?
Can you use algae to remove water pollutants?
How can you minimize the volume taken up by trash?
How much trash can be recycled or composted?
How far away from an animal pen do you need to be for there to be no fecal bacteria contamination of the soil or water?
What type of car antifreeze is most friendly to the environment?
What type of de-icer is most friendly to the environment?
How can you simulate acid rain?
How can you prevent soil erosion?
How much lead is in your soil? How much mercury is in your soil?
How does soil composition change with depth?
How much copper can plants tolerate?
Are there nontoxic methods that can be used to control mosquito populations?
How much electronic pollution is there in your home? Can you find a way to measure it?