Environmental science homework help

Earth Science Lab:In what order do materials settle in water? So this is my Topic: In what order do materials settle in water? Design and carry out an experiment to determine the order in which different sized materials (e.g., sand, gravel, topsoil) settle out in water after they have been mixed up. but i don’t understand the question below: What are some possible treatments you can use to answer your question? What are some variables that may influence your question, and are they variables that you can easily manipulate and test? What can i write about the possible treatments?