Universal Constants: A New Foundation of Measurement    >   Standardize - Achieve Precision

Accuracy vs. Precision - Focus on Precision

Watch the video Accuracy vs. Precision and consider these questions about precision.

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Title of Activity: Accuracy vs. Precision - Focus on Precision

Brief Description: Students watch a video of the NIST Role Models discussing accuracy and precision, and consider what is said about precision.

Target Grade Level: Grades 8-12

Discipline or Course: Physical Science

Estimated Time Required: 15-20 minutes

Individual / Partner / Group Work: Individual

Key Vocabulary:

  • Metrologist
  • Accuracy
  • Precision

Teacher Prep:

The video is placed in Lesson 1 because the terms are used at each station in Lesson 1 Engage - Meet the Measurements. It is also placed in Lesson 2, and it can be used at any point in the Mission.

The questions have three components:

  • Defining accuracy and precision.
  • Distinguishing between the terms accuracy and precision in daily life.
  • Understanding the significance of improvements in accuracy and precision.

Precision is repeatability. The example of using a gauge block to another environment is mirrored by the example of moving to a new scale.

Accuracy is defined as “correctness.” The last question in the journal prompt brings students back to the idea that new standards based on constants make measurements more accurate, but not necessarily more precise.

Possible Rubric

Area Novice Average Advanced
Understanding precision Response does not distinguish accuracy from precision Defines precision but not clearly illustrated in an example Precision is clearly defined with a relevant example
Connection to universal constants as standards No clear connection, or constants related to accuracy Constants are described correctly, but not connected to examples of precision Constants defined correctly and associated with precision (not accuracy) in the examples


Watch the video. Our Role Models at NIST discuss the difference between accuracy and precision. Then respond to these questions in your journal.

Accuracy vs. Precision

  1. What do the NIST Role Models say about precision?
  2. Do you feel like you understand the concept of precision better? Why?
  3. If you repeat a measurement every day and get the same result (within the limits of your tool), do you know your tool is precise? Here’s an example. You weigh yourself on your bathroom scale each day and get the same answer. Then you go to the doctor,and you weigh significantly more.
  1.  What does that tell you about the precision of your scale? What doesn’t it tell you? How can you determine which is more precise?
  2. Think of another example that illustrates the same idea.
  1. Today we are moving to using universal constants as standards for measurement. Does that contribute to the precision of our tools? Use your own example (from 3b) in your response.