Scientific Inquiry and Investigation Skills
Designing and Judging an Investigation
Every TASC inquiry question asks you to think like a researcher: what is being compared, what is held constant, and what evidence would settle the question? A strong investigation states a testable hypothesis, identifies one independent variable (the factor deliberately changed), one dependent variable (the measured outcome), and lists controlled variables kept the same so the comparison is fair. Ask whether the sample is large and representative, whether measurements are repeated, and whether the conclusion follows only from the data shown.
Measurement, Error, and Data Handling
Know the difference between accuracy (closeness to the true value) and precision (consistency among repeated readings). Random error scatters results and averages out with repetition; systematic error shifts every reading the same way, often from a mis-calibrated instrument or a zero error. Report values with sensible significant figures, convert units before calculating, and read graphs by naming axes, units, and trend. Tables should show repeats and a mean.
Traps to Watch
Questions often offer a plausible but confounded design, a conclusion that overreaches the data (correlation presented as cause), or a graph whose axes are swapped. Another common trap is a control group that is not truly untreated, or a claim that a single trial proves a pattern.
Worked Example
A student tests whether fertilizer affects plant height: ten plants get fertilizer, ten get plain water, all in identical pots and light. Fertilized plants average 18 cm, controls 14 cm. The independent variable is fertilizer, the dependent variable is height, and pot, light, and water volume are controlled. The conclusion is limited to these plants and this fertilizer dose; repeating the trial and randomizing plant placement would strengthen it. Rule of thumb: change one thing, measure one thing, keep everything else the same.