Answer:
When you are making a thesis, you are making a theory or a hypothesis. So, you start before you make the experiment. Tell the problem or subject that you are trying to discover or solve. Your theory has to be clear that shows the topic and that focuses on the experiment. When you write a thesis, use the words if and then, for example, "If I put dirty pennies in pickle juice then, it may be at least a little clean." After you are done stating your hypothesis, you clarify the variables.
I hope it helped.