Day 3: Conductivity Connection: Elements, Compounds & The Chesapeake


Students will be able to compare several months of conductivity data from 2 Baltimore streams to an in-class simulation of how chemical compounds affect stream water quality, in order to propose one REAL solution to local water pollution issues.

Lesson Overview

March 2010: Following the three major snow storms which occurred in the Baltimore region from December 2009 to February 2010, students examined data collected by BES Technician Dan Dillon from the same stream data classes had investigated in December. Through comparison of the data sets over several months, students discovered that Conductivity levels had sharply increased to values thousands of times greater than what they had found in the December 2009 “pre-blizzard” values. A hands-on activity students conducted as part of the March 2010 lesson included a simulation of point-source and non-point source pollution inputs resulting from hypothetical human activities which would be expected to occur along an urban or suburban waterway. In this activity, a clear, three-gallon container of water was placed at front of the classroom. Each student was given a small sample of a simulated substance that could reach a local stream as a result of nearby human activities. Ten different 2 oz simulated samples were prepared and sealed inside a 35 mm film canister. The samples were labeled so students knew in advance of the contents. To add an element of “change” to each, different amounts of “Blizzard Wizard” road salt (containing mostly KCl) was added, ranging from a trace to 2 teaspoons. This substance was added to include the road salt run-off component. The simulated samples ranged from diesel oil, gasoline and home insulation fiber to cigarette butts, waste solid food and beverages. Each time a student poured their simulated polluting substance in the water container, a Vernier Conductivity Meter and TI-83+/Lab Pro recorded change in the Conductivity levels. The student also read to the class a three sentence description of the situation which led to the substance being deposited in the local waterway. In each case, the human activities were presented as realistic actions that people have carried out. Examples included hikers throwing waste food and cigarettes in a stream, a suburban homeowner dumping waste oil or acute runoff from a salt pile in a roadway. At the conclusion of the activity, after ten different substances had been deposited in the simulated waterway, students were able to see that the Conductivity levels of the waterway, at approximately 3,000 microsiemens, were notably much higher than even their favorite sports drinks, observed at 600.

1 class period
  • Conductivity probe
  • Clear demonstration jars (film cannisters or baby food jars will work)
  • Road salt like "Blizzard Wizard"
  • Vegetable oil to simulate waste grease
  • Campfire ash
  • Food waste
  • Styrofoam to simulate asbestos
  • Soap suds
  • Coca Cola
  • Cigarette butts
  • Dark syrup to simulate engine oil
  • Coffee mixed with milk to simulate sewage
  • Be creative and think of other substances that you can simulate

Preparation: Assemble materials so that each team of students has one substance and its corresponding "Chesapeake Bay Substance Abuse" story.

1. Students will use their notes from “Makin’ Compounds” to describe 2 dangerous chemicals or items that may be washed into local streams after a big snowstorms. Students note if the substance is a solid or liquid, what’s in it and why it might be harmful to streams. Then they read a brief refresher on conductivity and compare trends in conductivity from 2 streams from Baltimore Ecosystem Study available data (see attached excel document or for data).

2. Students break up into teams and each team is given a substance and its corresponding "Chesapeake Bay Substance Abuse" story about how that substance gets into the Chesapeake Bay. Each team takes turns measuring the conductivity of their substance and sharing their substance story with the class. The students individually come up with a pollution solution to address the increased conductivity seen during wintertime at the Baltimore Ecosystem Study streams. The pollution solutions are shared with the class and the teams think critically about whether the proposed solutions are possible or not.

Cary Institute of Ecosystem Studies | Millbrook, New York 12545 | Tel (845) 677-5343

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