Read the variable the experiment changed
- The idea
- Predict
- See it
- Why
- Check
The idea
“Any pattern I can spot in the table is something the experiment showed.”
Water and soil matter to plants, so a claim about them sounds true. In this experiment they were the same for every group, so they can't be why the results differ.
The short version
The mistake: Any pattern I can spot in the table is something the experiment showed.
What's actually true: An experiment can only show the effect of the variable it changed. A column held constant can't explain why groups differ.
- The independent variable is the one changed on purpose, here hours of light. Dry mass is the dependent variable, the one that responds.
- Variables held constant, like water and soil, are called controlled variables.
- A claim about water or soil might still be true. This data just can't support it.
On the exam: Before you answer, find the column that changes. It's the only one the results can speak to.