Lesson 15

Error Intervals

Lesson Narrative

This lesson is optional. In this lesson, students find and analyze intervals of possible error based on maximum possible errors.

This material gives students a solid foundation for future work in statistics. It is not necessary at this stage to emphasize the idea of a margin of error which defines a range of possible values. It is enough for students to see the values falling into that range, as preparation for future learning.

Learning Goals

Teacher Facing

  • Comprehend that manufacturers often define a maximum acceptable percent error for characteristics of their products.
  • Determine what information is needed to solve a problem involving percent error. Ask questions to elicit that information.
  • Generate values that fall within the acceptable range for a measurement, given a maximum percent error.

Student Facing

Let’s solve more problems about percent error.

Required Preparation

Print and cut cards from the Info Gap: Quality Control activity blackline master. One copy of the blackline master will be used for every 4 students. 

Learning Targets

Student Facing

  • I can find a range of possible values for a quantity if I know the maximum percent error and the correct value.

CCSS Standards


Glossary Entries

  • measurement error

    Measurement error is the positive difference between a measured amount and the actual amount.

    For example, Diego measures a line segment and gets 5.3 cm. The actual length of the segment is really 5.32 cm. The measurement error is 0.02 cm, because \(5.32-5.3=0.02\).

  • percent error

    Percent error is a way to describe error, expressed as a percentage of the actual amount.

    For example, a box is supposed to have 150 folders in it. Clare counts only 147 folders in the box. This is an error of 3 folders. The percent error is 2%, because 3 is 2% of 150.

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