Academic journal article The Science Teacher

How Accurate Are Student-Collected Data? Determining Whether Water-Quality Data Collected by Students Are Comparable to Data Collected by Scientists

Academic journal article The Science Teacher

How Accurate Are Student-Collected Data? Determining Whether Water-Quality Data Collected by Students Are Comparable to Data Collected by Scientists

Article excerpt


Measurements of water quality can provide scientists with valuable information about a tidal creek and its watershed, including effects of nonpoint and point-source pollution, drought conditions, and other water-quality issues. In Georgia, the Adopt-A-Stream program was implemented by the Georgia Department of Natural Resources to increase public awareness of water-quality issues, provide citizens with tools and training to evaluate local waterways in their community, and encourage partnerships between citizens and their local government. Throughout the state, trained volunteer groups collect baseline water-quality data that could potentially be used to help government officials make educated decisions about environmental issues.

Many student groups, ranging from elementary to college level, participate in the Adopt-A-Stream program. Monitoring programs that involve students in the data-collection process can provide benefits to students, teachers, and local scientists. Involvement in a monitoring program requires students to use scientific reasoning and critical-thinking skills to investigate the relationship between environmental quality and the organisms that live in that particular habitat. The data collected by such programs--if the data are collected accurately--can be presented to the community to assist in making informed decisions regarding local environmental issues. Few studies, however, have been published about the accuracy of student-collected data. The purpose of our study was to teach upper elementary (5th grade) and high school students (10th-12th grade) to monitor two estuarine creeks using an adaptation of the Adopt-A-Stream protocol. Data collected by students were then compared to data collected by a trained instructor to determine the accuracy of student-collected data for dissolved-oxygen (DO) concentration, salinity, and water temperature. (Editor's note: For another example of student participation in a water-monitoring program, see "Making Science Relevant" by Eick et al. on p. 26 of this issue.)

Materials and methods

For our study, three elementary classes and three high school classes completed an in-class, 45-minute lesson on the proper techniques for collecting water-quality data before visiting the field. The instructor, a scientist trained in the Adopt-A-Stream protocol, demonstrated the process for data collection to each class and then allowed students to practice using water samples collected by the instructor prior to the session. During this session, the instructor also discussed safety procedures and the importance of rigor in the scientific process (Safety note: see "Safe practices for water-quality field studies," p. 33). Within two weeks of the in-class lesson, each class collected water-quality data at one of two creek sites in Savannah, Georgia (Lazaretto Creek or Betz Creek). All data were collected between April and December 2005.

On the sampling date, students were divided into three or four groups and directed to collect data using the instructions and materials provided to them. DO levels were measured using an analysis kit, and one of the three high school classes also titrated samples for DO levels using a titration kit. Salinity was measured to the nearest 1 ppt using a refractometer, and water temperature was measured to the nearest whole degree Celsius using a stem thermometer. For all tests, students were required to record a numerical value using the units marked on the kit or instrument. For the colorimetric DO kits, which provide several color samples that must be matched to the color of the tested sample, students were instructed to choose the value that corresponded to the best color match.

Student groups in each class collected data for all parameters on two replicate samples of water, producing two values per student group for each parameter. These values were combined with values from the other student groups to produce a class average for each parameter for that sampling date. …

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