Teaching Error Tolerance using Absolute Value Equations and Inequalities

The goal of this Algebra 1 lesson is for students to learn about absolute value equations and inequalities, and their real-life application to error tolerance. Error tolerance is the process by which Lockheed Martin engineers ensure mechanical parts meet specifications. During my fellowship at Lockheed Martin, I learned that every part engineers work with has to undergo thorough error tolerance testing.

During the lesson, students measure different parts from a hardware store, such as nuts, bolts, washers, and electrical straps. They will then apply an "error tolerance test" to see which parts meet the specification. The goal of this lesson is for students to represent error tolerance using absolute value inequalities. For example: "NASA has decided that their Standard for bolts used on their satellite should have a bolt head diameter of 0.5 inches. NASA will only use bolts that have a diameter that falls within 0.25 inches of the standard. Measure out all the bolt heads to see which ones can be used and which should be thrown out. Then write an absolute value inequality to represent this situation." [Answer: x-0.5‰¤0.25] Students learn why checking for error tolerance is important for parts going onto airplanes, spaceships, and satellites.

Students will end up writing absolute value inequalities for 5 different scenarios, each one involving a washer, bolt, hexagonal nut, or electrical strap.