Does anyone know what a control or variable is?

it is for science fair and i need help with the control variable and analysisDoes anyone know what a control or variable is?
Oddly enough, this actually can work in the math section of this website. . .





Anyway, a control is something in an experiment which does not change through multiple trials (for example, in a study about how well a type of plant grows in a certain type of soil, the same type of plant will be used in each experiment with different types of soil; in that experiment, the control is the plant). A variable is whatever changes in an experiment through multiple trials (for example, in the aforementioned study on plant growth, the type of soil is the variable).





Anyway, this is similar to something in math. . .variables change, and constants (controls) do not.Does anyone know what a control or variable is?
The variable is what is changing and the control is what you have control over...





so...i believe if you are trying to see what plant food works better then your controls would be:


the seed, the pot, the soil, the amount of water...this is the same for each


the variable would be the food...it is different in each
In order to learn anything from an experiment, you should only change one thing at a time. The thing you change is called the ';variable';. The ';control'; is the thing you don't change, or a sample in your experiment with a result which you already know the outcome for. Only by comparing the variable results to the control results can you make a meaningful conclusion.





For example, let's find out which liquids freeze in your household freezer. Your variable would be the material (orange juice, milk, cola, beer, vodka). You should keep all other factors the same (volume of liquid, shape of container, initial temperature of the liquid, location inside the freezer, time spent inside the freezer, etc.). Your control might be a sample where the liquid is water. Since you know the temperature at which water freezes, that gives you something to compare the other results to. You could determine which materials freeze faster than water, or do not freeze at all in your freezer. If you inspect your samples and the water is not frozen, you know to wait longer, or perhaps your freezer is not functioning properly.





The control helps you determine if the experiment performed as designed. If the control doesn't produce the results you expect, you can't draw any conclusions from any of the variable samples.
In science, you want to demonstrate the validity of a theory, or proposition. First you must state the theory. Then you must design an experiment to test that theory. A good experiment varies one factor, or condition, called the variable. If you have more than one variable, you will not be able to tell which one or ones are affecting the outcome.





To make your experiment even better scientifically, you establish a control component, which is to say, you have the same elements and processes as the experiment, but you do not introduce the test variable (or any other variable, except time, if you can). That way, you show that only the variable affects the outcome of your experiment (if indeed it does so), and can measure how it does so.
It is the aspect of the experiment that you change. When you change th value of the control variable, you get a change in the dependant variable. This way you can state that the control variable is important.