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Water Quality-Total Dissolved Solids

This activity is taken from Earth Science With Vernier by Robyn Johnson, Gretchen Stahmer DeMoss, and Richard Sorensen, Published by , Vernier Software (more info) . This Starting Point page was created by Robert MacKay, of Clark College.
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This activity was selected for the On the Cutting Edge Reviewed Teaching Collection

This activity has received positive reviews in a peer review process involving five review categories. The five categories included in the process are

  • Scientific Accuracy
  • Alignment of Learning Goals, Activities, and Assessments
  • Pedagogic Effectiveness
  • Robustness (usability and dependability of all components)
  • Completeness of the ActivitySheet web page

For more information about the peer review process itself, please see http://serc.carleton.edu/NAGTWorkshops/review.html.


This page first made public: Jun 29, 2005

This material was originally created for Starting Point:Introductory Geology
and is replicated here as part of the SERC Pedagogic Service.

Summary

Students use a microcomputer connected to a conductivity probe to measure the total dissolved solids in local area water samples. Students then compare their measurements with others in their class as well as other standard measurements.

Learning Goals

Context for Use

This activity can be used as a lab activity in an introductory geoscience course that contains a discussion of ocean salinity, hydrology and/or water quality.

Instructors can also easily incorporate aspects of this activity into an interactive lecture.

Description and Teaching Materials

This activity requires a microcomputer, multi-sensor interface, and conductivity probe. The specific activity is included in Earth Science With Computers by Robyn Johnson, Gretchen Stahmer DeMoss, and Richard Sorensen published by Vernier Software (more info) , with a site license for $45.00. The complete activity in pdf format can be viewed at Water Quality-TDS (Total Dissolved Solids) The cost of the interface and conductivity probe are $220 and $89 respectively.

Students can also use a graphing calculator with the interface and conductivity probe.

Comparable equipment can also be purchase from Pasco Scientific.

Teaching Notes and Tips

This activity will take approximately 2 hours to complete in a lab setting with some extra time possibly needed for students to summarize their results. The activity description at Water Quality-TS (Total Solids) comes complete with two pages of Teacher information.

Doing parts or all of this activity as an interactive lecture is also an option.

This activity can also be done in three phases and in conjunction with a water quality pH activity which is also in Earth Science With Computers. First, a protocol is established for water sample collection either in lecture or as part of a lab activity. Next, students go out on their own or in small groups to collect water samples from different water bodies in their local area. Finally, students perform measurements of TDS and pH in the lab followed by a summary of all results and a debriefing.

Assessment

The activity comes with very specific instructions. Assessment is most easily accomplished by reviewing student results and with a follow up discussion of all results. Having students design their own experiment for an "Extension" investigation can also help you better assess their ability to synthesize what they have learned and apply it to a slightly different situation.

References and Resources

Vernier Software (more info) has several other sample geoscience labs from Earth Science With Vernier available in pdf format as examples at other examples. These include "Where is North", "Reflection and Absorption of Light", and "Comparing Sunscreens"

Pasco Scientific has about 13 online lab activities available for free. These are mostly geared towards high school students but can easily be modified for an introductory college level course as either a laboratory activity, a special project, or an interactive lecture example.

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