Final answer:
In an experiment, the target variables are usually the unknowns that are being measured or observed. The unknowns that are being manipulated are called independent variables. The unknowns that are being controlled are called control variables.
Step-by-step explanation:
In an experiment, the target variables are usually the unknowns that are being measured or observed. These are the variables that are being investigated and their values are recorded or observed. For example, if you are conducting an experiment to determine the effect of temperature on the rate of a chemical reaction, the temperature would be the target variable that is being measured.
The unknowns that are being manipulated are called independent variables. These are the variables that are intentionally changed or varied in the experiment. In the same example, if you are changing the temperature levels to see how it affects the reaction rate, the temperature would be the independent variable.
Finally, the unknowns that are being controlled are called control variables. These are the variables that are kept constant or unchanged throughout the experiment. They are used to ensure that any changes observed in the target variable are solely due to the independent variable and not influenced by other factors. In the example, factors like the concentration of reactants, pressure, or catalysts could be controlled variables.