Test those predictions by experiments or further observations. Modify the theory in the light of your results. Go to step 3. A key ingredient of the scientific method is the hypothesis. Educated prediction as a tentative answer to a specific question or problem.
Hypotheses are tentative explanations for observations or solutions to problems.
Hypotheses are not just blind propositions, but are educated predictions based upon available evidence. Predictions made from hypotheses must be testable by making observations or performing experiments. This limits the scope of questions that science can answer. Hypotheses can be eliminated, but not confirmed with absolute certainty. If repeated experiments consistently disprove the predictions, then we can assume that the hypothesis is false.