Accuracy, Precision, Variation and Tolerance Module

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## Overview

This unit plan was designed to introduce students to the concepts of variation, accuracy, and precision in a real-world setting with a focus on measurements and spreadsheets. The lessons should require five days in total, possibly six if students have never worked with a spreadsheet program in the past. The sample spreadsheet included was prepared on Excel 5.0, and the functions described herein pertain to that program. However, if the instructor prefers or only has access to a different spreadsheet, only minor adjustments should be required to make use of this unit plan.

For Davea students, in particular, the emphasis is on the concept of tolerance (the range of variation permitted in maintaining a specified dimension in machining a piece). The problem statement is applicaple at the automotive shop in which the goal, in this case, is to perform cylinder head services for several types of vehicles. The Davea students measure the valve guides and valve stems, and they record their measurements in a spreadsheet that is also accessed by the other high school students in DuPage county. After the Davea students compare them with the factory specifications they determine the tolerance. Then, they compare the tolerance for several cars that are manufactured from the same company. They enter these data on a spreadsheet that is accessed by everyone. The question is whether there are any trends in the variation of the tolerance for certain manufacturers?

The Problem:

(For Davea students) You are asked by your employer at the automotive shop you work to perform cylinder head services for several types of vehicles. After you measure the valve guides and valve stems, you record your measurements, and you compare them with the factory specifications. Find the tolerance (the range of variation permitted in maintaining a specified dimension in machining a piece). Compare the tolerance for several cars that are manufactured from the same company. Enter the data to a spreadsheet so that high students from the DuPage county can access them. The question for everyone is: Do you find any trends in the variation of the tolerance for certain manufactures?

Timeline:

●
1st Day--Become familiar with the difference between accuracy and precision
● 2nd Day--Measure valve guides and valve stems and record the measurements to a spreadsheet
● 3rd and 4th Days--Students will use a spreadsheet to analyze automotive data
● 5th Days--Variation, Variance and Standard Deviation.