Science Buddies: "Ask an Expert"

I'm doing my science fair project on salinity. Should I use both salinty and water temperature as variables?

Thank you,
Alec

Firstly, I would recommend making further posts in the Grade 6-8 Physical Science forum, this way experts with knowledge in your field of study will be able to help you.
I see that your experiment is determining the level of salinity required for different objects to float. In this case, you should not use temperature as a variable. If you altered the water temperature, you would not be sure if the change in buoyancy is a result of the change in salinity or because of the change in temperature. You should keep the temperature constant and the amount of salt in the water should be your independent variable (the variable that you change). Your dependant variable will be the density of the material that is able to float at each level of salinity.

Hope this helps, and Good luck with your project,
Nithin T