By Kirk Anderson and Mary Richardson, Grand Valley State University
Overview of Lesson
In 2014, a crisis began when the city of Flint Michigan switched its water supply in an effort to save money and the water became contaminated with lead. The EPA’s Lead and Copper Rule states that if lead concentrations exceed an action level of 15 parts per billion (ppb) in more than 10% of customer taps sampled, then actions must be undertaken to control corrosion and the public must be informed. From this, we see that the “action level” of 15 ppb is compared with the 90th percentile of the data. In this lesson, students will (1) read two news stories about the Flint water crisis and answer questions to demonstrate understanding of the articles, (2) compute the 90th percentile using two data sets (with and without outliers), (3) discuss the computations, (4) use CODAP or other software to create a dot plot, and (5) write a report tying it all together.
Download: PDF Lesson Plan
Download: Activity Handout
Download: Flint Data Set
Download: Excel Directions