A good school project starts with curiosity, but a question alone is not enough to guide an experiment. To test an idea fairly, you need to turn the question into a hypothesis that predicts what will happen. A strong hypothesis connects one factor you change to one result you measure.
This makes your project clearer, easier to organize, and more scientific.
Key Facts
- A testable hypothesis predicts a relationship between an independent variable and a dependent variable.
- Use the template: If the independent variable changes, then the dependent variable will change, because of a scientific reason.
- A strong hypothesis is measurable, falsifiable, specific, and predicts a direction.
- Independent variable = the factor you change on purpose.
- Dependent variable = the outcome you measure or observe.
- Controlled variables = factors kept the same so the test is fair.
Vocabulary
- Hypothesis
- A hypothesis is a testable prediction that explains what you think will happen in an experiment and why.
- Independent Variable
- The independent variable is the factor the experimenter changes on purpose.
- Dependent Variable
- The dependent variable is the result that is measured to see what effect the change had.
- Falsifiable
- A falsifiable statement can be shown to be wrong by evidence from an experiment or observation.
- Controlled Variable
- A controlled variable is a factor kept the same so the experiment tests only the main change.
Common Mistakes to Avoid
- Writing a question instead of a hypothesis is wrong because a question does not make a clear prediction. Change “Does light affect plant growth?” to “If plants receive more hours of light, then they will grow taller because light helps photosynthesis.”
- Using vague words like better, more, or faster without measurements is wrong because the result cannot be judged clearly. Replace vague terms with measurable outcomes such as height in centimeters, time in seconds, or mass in grams.
- Changing more than one variable at a time is wrong because you cannot tell which change caused the result. Test one independent variable while keeping other important conditions the same.
- Making a hypothesis that cannot be proven wrong is wrong because science needs evidence that could support or reject the idea. “This fertilizer is the best” is weaker than “If plants receive fertilizer A, then their average height after 14 days will be greater than plants with no fertilizer.”
Practice Questions
- 1 A student asks, “Does studying with music affect quiz scores?” Write a testable If...then...because hypothesis using quiz score out of 100 as the measured result.
- 2 A student tests how the amount of water affects bean plant growth. The plants receive 20 mL, 40 mL, or 60 mL of water each day for 10 days. Identify the independent variable, dependent variable, and two controlled variables.
- 3 Compare these two statements: “Do sports drinks help athletes?” and “If students drink 250 mL of sports drink before running, then their 400 m run time will decrease because the drink provides water and sugar for energy.” Explain which is the better hypothesis and why.