Apply the full scientific method (question, hypothesis, controlled variables, data, conclusion) to design and present an original investigation drawing on any unit from the year.
A science fair project carries the scientific method all the way through, from a real question to a real conclusion. It starts with a testable question, a hypothesis -- a specific, testable prediction, not just a guess -- and an experiment with one independent variable (deliberately changed), a dependent variable (measured), and controlled variables (held constant so the test is fair).
After collecting real data, the conclusion has two jobs: state whether the data supported the hypothesis, and explain why, using the actual numbers collected. A strong project from any unit this year -- forces, energy, waves, or space -- can become a genuine investigation using exactly this structure.
Mastery looks like: They design or describe a complete investigation with a testable hypothesis, correctly identified variables, realistic data, and a conclusion referencing both the hypothesis and the data.
Common stumbles: Writing a hypothesis that cannot actually be tested; forgetting to control other variables; writing a conclusion that ignores data that did not match the hypothesis.