* "Controlled variable" usually refers to an experiment. In an experiment, you change one thing (the independent variable), observe the effect on something else (the dependent variable), and keep everything else the same (the controlled variables).
* Oil and water are substances, not variables. They are the things you might be studying, not the things you are controlling.
Here are some possible interpretations of your question:
* If you're thinking about an experiment where you mix oil and water, then the controlled variables would be the things you keep constant. For example:
* The temperature of the water and oil.
* The amount of water and oil you mix.
* The type of oil.
* If you're thinking about the properties of oil and water themselves, then "controlled variable" doesn't really apply. The properties of oil and water are what they are, like their density, viscosity, and chemical structure. These are not things you control in an experiment.
To be more helpful, please tell me:
* What specific experiment are you interested in?
* What are you trying to find out about the relationship between oil and water?
Once I know this, I can help you identify the controlled variables in your experiment.
