Science as Inquiry
What to Know
Science as Inquiry tests how scientists ask questions and how evidence supports conclusions. Know the parts of an experiment: a hypothesis is a testable prediction; the independent variable is what the experimenter changes; the dependent variable is what is measured; controlled variables are kept constant; and a control group receives no treatment or a standard treatment for comparison. Distinguish observations (direct data) from inferences (interpretations). Understand that reliable results require repeated trials, adequate sample size, and unbiased sampling. Be able to read tables and graphs: identify axes, units, trends, and outliers.
Traps
- Calling any kept-constant factor a control group. A control group is a comparison group; controlled variables are constants.
- Confusing correlation with causation.
- Confusing independent and dependent variables when a graph places the independent variable on the x-axis.
- Assuming a single trial proves a hypothesis.
- Ignoring sample size, bias, or whether data are qualitative vs quantitative.
Worked Example
A student tests whether fertilizer affects plant height. She grows 20 plants: 10 get fertilizer, 10 get none; all receive the same light and water. Independent variable: fertilizer amount. Dependent variable: plant height. Control group: plants without fertilizer. Controlled variables: light, water, soil, pot size. Rule of thumb: change one variable, measure one result, and keep everything else the same.