Lettuce not be salty: An update of a common secondary education experiment measuring seed germination under salt-stressed conditions

Abstract

Assessing the ecological impact of deicing roadways is a well-documented high school and undergraduate toxicology laboratory experiment. Most commonly, this experiment has been done using different concentrations of rock salt (NaCl) as the toxicant/deicer and buttercrunch lettuce seeds for the bioassay. However, as we are becoming a more environmentally conscious society, people, businesses, and city governments have explored substituting NaCl as a deicer for more eco-friendly alternatives, although the impact of these rock salt alternatives have not been well explored in the literature or in the classroom. Thus, the aim of this article is to update the common deicer experiment by having students compare the toxicity of rock salt to that of two different rock salt alternatives (beet salt and calcium chloride, CaCl2). The students then have to provide a recommendation for which deicer to use under different scenarios (for a homeowner, for a business, and for a city) and defend their choices based on an extensive literature search. By designing this experiment to have the students defend their recommendations, they will be utilizing higher-level thinking per Bloom’s Taxonomy, and they will be getting additional hands-on laboratory training in making solutions and performing serial dilutions by examining three deicers rather than just one. Thus, we believe that our update to this laboratory exercise should be considered for faculty interested in having their students conduct toxicology-based laboratory experiments.