Fair test – planning an experiment and controlling variables
Integrated ScienceScientific Skills & MeasurementAges 11–12
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Sign in to playChoose an investigation (dissolving sugar, a toy car rolling down a ramp, seedlings growing) and decide which factor to change (independent variable), which to keep the same (control variables) and what to measure (dependent variable). The simulation runs each trial with random variation, calculates means, flags anomalous results and warns when two factors change at once. Students then draw a conclusion from the results table.
Lesson: Scientific enquiry: planning a fair test; independent, dependent and control variables
What it shows
A fair test changes only one factor, the independent variable, keeps every other factor the same as control variables, and measures one quantity with a number, the dependent variable. This simulation offers three investigations based on simple empirical models: the time for sugar to dissolve, the distance a toy car rolls across the floor, and the mass gained by a seedling in 14 days. Each trial includes random variation like a real experiment, and occasionally an anomalous result appears. Repeating trials and taking a mean, while leaving out anomalies, gives more reliable data.
How to use
Pick an Investigation, then for each factor set the Role to Change or Keep the same and choose the value to keep. Choose what to Measure and the number of Repeats per level, then press Run experiment. The results table fills in trial by trial, and the chart shows each result and the mean. Try changing two factors to see an unfair test. Finally, choose a trend under Conclusion and press Check.
Parameters you can change
- Investigation How fast sugar dissolves, Toy car rolling down a ramp, Seedling growth
- Repeats per level 1–5 times
- Random variation 0–25 %
- Show plan checklist
Questions to explore
- Why should only one factor be changed in each experiment?
- Why is it better to repeat each measurement at least three times and calculate a mean?
- Does the mass of the car affect how far it rolls, and how could you be sure?
