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The development of proficiency in the practices used by scientists and engineers is considered an important student outcome of laboratory instruction. We developed tasks to assess students' use and development of selected scientific and engineering practices in the general chemistry laboratory using an adapted evidence-centered design approach. In this paper, we provide a detailed description of the process of development and validation of these assessment tasks, using one of our tasks to illustrate the process. The tasks show strong evidence of validity and reliability for revealing students' understanding of scientific and engineering practices within the research context.

We have applied density functional theory in statistical mechanisms to study the heterogeneous nucleation of supersaturated vapors on spherical aerosol-like substrates. Our calculations reveal the inadequacy of the classical nucleation theory in describing the condensation of droplets on very small particles. The latter approach is particularly inaccurate both at high supersaturations and in the vicinity of the wetting transition. Comparisons are also made with recent experimental results for the condensation of supersaturated vapors on submicrometer particles.

The knowledge of historical facts can help teachers and students to correctly appreciate a variety of scientific theories. It is important to be aware of the evolution of the basic concepts, particularly the ones our students find very abstract and therefore difficult to understand. Historical knowledge of chemical concepts will allow us to understand their difficulties and make them easier to teach successfully. In this paper we answer the following research questions: what was the historic and sociologic context in which chemical equivalent, mole and its magnitude amount of substance were introduced to science? How the lack of historic knowledge in science teaching contributes to the presence of distorted views of science and hampers meaningful learning?