Science Buddies: "Ask an Expert"

Hi! I am doing the project how does soil affect the pH of water listed on https://www.sciencebuddies.org/science- ... background

I am just a bit confused on what I am finding and what I should change. For my project, I am required to have an independent variable and a dependent variable. Is the independent variable the type of soil or the amount of time the soil stays in contact with the water? If I choose either one, how will I have to change the experiment?

Thank you!

Hi! Based on how the procedure is given in the link you posted, it looks like both soil and and amount of time in contact with the water are independent variables:

1) You're testing how one type of soil affects the pH of the water after 1 hour, 1 day, and 2 days, making time the variable within this portion of the experiment.

2) You're doing the same experiment with two additional soil samples, letting you compare how different types of soil affect water pH.

I hope that helps clarify the experiment for you, and let me know if you still have questions!