Data and Evidence
7th Grade Science · 6 lessons
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Lessons
- 1Accuracy Versus PrecisionAccuracy describes how close a measurement is to the true value, while precision describes how close repeated measurements are to one another. A trustworthy result should be both accurate and precise.Lesson
- 2Systematic Error Cannot Be Averaged AwayRepeating a measurement reduces random scatter but does nothing to a systematic bias. A balance reading 2 g high reads 2 g high every time, so the mean of a hundred repeats is still 2 g wrong. Only checking the instrument fixes it.Experiment
- 3Percentage UncertaintyAbsolute uncertainty is the ± on a measurement; percentage uncertainty is that divided by the measurement, times 100. The same ±1 mm matters far more on a 5 mm length than on a 500 mm one, which is why measuring a bigger sample improves precision.Experiment
- 4Writing a Conclusion That the Data SupportsA conclusion states what was found, how confident you are, and what it does not show. Overclaiming — turning a small correlation into a law — is the fault examiners and reviewers catch most often.Lesson
- 5Why Results Get PublishedPublishing puts a method and its data where others can attack them. That is uncomfortable and entirely the point: an idea that survives serious attempts to break it is worth more than one nobody has tested.Lesson
- 6Estimating to Check an AnswerBefore trusting a calculated result, estimate it roughly in your head. If the calculator says a person's mass is 7,000 kg, the arithmetic is wrong, and a five-second estimate catches what a careful recalculation might not.Lesson
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