That's a very interesting and important topic. Can you give a little more background information? What is your school grade level? What procedures do you plan to use to test your hypothesis? Do these containers have identical dimensions? Will the containers be exposed to sunlight? Will they be inside or outside? The more information you provide, the more the experts here will be able to help.
It will also be helpful for you to read more information about the process of evaporation. This web page has a decent summary http://www.newton.dep.anl.gov/askasci/c ... m00964.htm
You can find more information by conducting a web search for "evaporation", "evaporation factors", or other relevant terms. If you encounter any terms or concepts that you don't understand, please feel free to ask us for help.