Grades 5–8
Identifying Variables Practice
Practice recognizing independent, dependent, and controlled variables through real science scenarios.
Experimental design · Grades 5–8
Science Experiment Mistake Finder
Help students identify problems in experiments, evaluate fair tests, and explain how scientific investigations can be improved.
Ready to practice?
Choose a grade, topic and difficulty, then select Start New Practice.
What is an experiment mistake?
An experiment mistake is any problem in how an investigation is planned or carried out that makes its results less trustworthy. Examples include changing too many things at once, measuring carelessly, or drawing a conclusion the data does not support.
What makes an experiment a fair test?
In a fair test, only the independent variable changes. Everything else — the controlled variables — stays the same, so any difference in the results can be linked to the one factor that changed.
Common scientific experiment mistakes
These are the mistakes students meet most often:
- Changing more than one variable at a time
- Comparing groups that started out different
- Using inconsistent or imprecise measurements
- Running only one trial
- Drawing conclusions the data does not show
How to use these worksheets in class
Use one scenario as a warm-up, ask pairs to compare their fixes, or assign a full worksheet before students plan their own investigation.
Examples
Uncontrolled variable
Testing two fertilizers, but one plant sits by a window and the other in a dark corner.
Measurement error
Timing a race with a stopwatch for one runner and by counting seconds out loud for another.
Unsupported conclusion
Testing one brand of paper towel and concluding it is the most absorbent of all brands.