The nature, occurrence and analysis of water pollutants is interesting chemically and relates well to the interdisciplinary nature of the modern chemistry curriculum. The issue is of worldwide significance and affects both wealthy and poor nations. In the first part of this paper we present an overview of water pollution in the United States and Mexico, including sources, federal regulations and standards, and standard methods for the assessment of overall water quality. The second part of the paper focuses on three water pollutants, lead, atrazine, and nitrate. We chose these as important representative examples of heavy metals, organic herbicides and inorganic pollutants. In addition to a background discussion of each substance and analysis methods for it, we describe laboratory activities that are suitable for the high school audience.

These logic puzzles were field-tested with a diverse audience in the general chemistry classes at the University of Nebraska-Lincoln and were found to be challenging and fairly enjoyable. In this paper we describe and give several examples of logic puzzles.

The Orange Juice Clock, in which a galvanic cell is made from the combination of a magnesium strip, a copper strip, and juice in a beaker, has been a popular classroom, conference, and workshop demonstration for nearly 10 years. The discussion that follows considers the recent history, chemistry, and educational uses of the demonstration.

This study examines an example of the alternative conceptions and conceptual errors of students at the higher education level in a scientific context. It begins by introducing the significance and characteristics of preconceptions and alternative ideas or alternative conceptions, highlighting their impact on students’ misconceptions. Using the dissolution of a gas (oxygen) in a liquid (water) as the case study, and based on the answers to a questionnaire, this work analyzes the responses by university students which, in most cases, lack scientific rigor. The questionnaire used in this study has been designed in such a way that students provide three types of answers: the first is a yes/no/do not know question; the second is a short answer question to briefly explain the previous answer; and the third is a drawing answer question in which students are required to interpret the phenomenon at the molecular level by drawing a picture. Surprisingly, minimal differences were observed between the university students enrolled in Bachelor’s degree programs (Chemical Engineering or Industrial Engineering) and Master’s degree programs (Master’s Degree in Teacher Training), over the five years (from 2018/19 to 2022/23) covered by this study. Only about 11% of the students provided acceptable reasoning, while the rest demonstrated alternative conceptions. These alternative conceptions encompassed concepts such as the formation of oxygenated water instead of the dissolution, the belief that gases do not dissolve in liquids, confusion about atomic and molecular levels, difficulties in interpreting scientific language, and reliance on simplistic and naïve ideas, among others. After the teacher’s review, the questionnaire and students’ answers were discussed in class in order to detect and correct errors. Approximately one month later, the students were asked to repeat the same questionnaire, when it was observed that the number of correct answers, showing adequate reasoning, had increased to 75%. The results of this study, using a very simple questionnaire that only takes 10 min, could be valuable for guiding teachers to question and transform their pedagogical content knowledge in order to improve the transmission of scientific content, which may involve difficulties that, a priori, were not expected in university students.

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