Lesson 1.5: Accuracy vs. Precision (Significant Figures)

In this lesson, we break down the important (and often confusing) difference between accuracy and precision in scientific measurements.

Using clear examples, data sets, and visual models, you’ll learn how to:
-Tell whether a set of measurements is accurate, precise, both, or neither
-Explain your reasoning using experimental data
-Connect precision to significant figures
-Use percent error to evaluate accuracy
-Understand why accuracy and precision describe different qualities of measurements

We’ll also explore common misconceptions—like why measurements can be very consistent but still wrong—and why scientists care about both accuracy and precision when collecting and analyzing data.

Key topics covered:
-Accuracy vs. precision (definitions & examples)
-Repeated measurements and data patterns
-Significant figures as a measure of precision
-Recording calculated values with the correct number of significant figures
-Percent error and comparison to true values

This lesson builds essential skills for lab work, density calculations, and future data analysis throughout chemistry.

👉 Tip for students: As you watch, practice explaining why a result is accurate or precise—not just choosing the label.