Create a hypotheses about the universe must be tested against reality.
Correctly write an “if-then” hypothesis.
Explain the difference between a dependent and independent variable.
"If _____[I do this] _____, then _____[this]_____ will happen."
We make an a testable prediction AKA the famous phrase "educated guess."
We write a hypothesis.
We set out to prove or disprove the hypothesis.
What you "think" will happen, of course, should be based on your preliminary research and your understanding of the science and scientific principles. In other words, you don't simply "guess." You're not taking a shot in the dark. You're not pulling your statement out of thin air. Instead, you make an "educated guess" based on what you already know and what you have already learned from your research.