A valid experiment must be _________?

• A. measurable
• B. significant
• C. repeatable
• D. colorful

Answer: (A)

Being able to quantify observations is essential for a valid experiment. Measurements turn what you observe into data you can analyze, compare, and test statistically. When outcomes are measurable, you can determine how big the effect is, how it compares to a control, and whether any observed difference is likely due to the manipulated variable rather than random variation. Without measurement, conclusions would be subjective and the results would lack interpretable, testable meaning.

Significance relates to whether results are unlikely to be due to chance, which is about statistical interpretation, not whether the experiment yields usable data. Repeatability concerns consistency across trials, contributing to reliability but not guaranteeing that the experiment actually measures what it intends to measure. Colorfulness has no bearing on the scientific validity of the results.