Abstract
Student-centered teaching allows students to be actively engaged in hands-on, minds-on activities that emphasize creativity and collaboration, enabling them to ask questions and design their own investigations to real-world problems. One such problem is water contamination, which causes human health and environmental issues. However, chemical water quality testing for pollutants can be timely and expensive. In addition to chemical testing, researchers have developed assays using unicellular organisms to determine which pollutants are present and in what concentrations. In this three-hour laboratory activity, high school students and undergraduate biology or microbiology students work in pairs to help a fictional company develop a water quality microbioassay. Students design their own laboratory protocols to test the reaction of a bioluminescent bacterial species (i.e., Photobacterium phosphoreum or Aliivibrio fischeri ) to exposure of common aquatic pollutants such as fertilizer, household cleaners, and motor oil. During this laboratory activity, students apply previously learned components of experimental design, including positive and negative controls, constants, and experimental groups. In addition, students gain experience writing a scientific explanation for a recommendation regarding the bioluminescent bacteria's suitability in a bioassay. Pre- and post-evaluation data revealed that students were successful in achieving the activity's objectives as well as in designing their investigations and writing their protocols using scaffolds within the lesson.