In this paper we describe the learning process of a group of experienced chemistry teachers in a specially designed workshop on molecular symmetry and continuous symmetry. The workshop was based on interactive visualization tools that allow molecules and their symmetry elements to be rotated in three dimensions. The topic of continuous symmetry is a new field of study that provides a quantitative description of the distance of a specific structure from perfect symmetry. Using novel online tools, teachers were able to perform these calculations with the emphasis on the chemistry, rather than on the mathematics of the calculations. Our results show that even a very basic knowledge of symmetry and continuous symmetry opens up new ways of thinking about and looking at molecules. The addition of visualization tools creates a deeper understanding of molecular structure. Moreover, even though molecular symmetry is not a mandatory part of the chemistry high-school curriculum in Israel, familiarity with concepts of symmetry can help teachers understand and explain other topics, such as chirality and the polarity of molecules. Our results indicate that highly advanced content can influence the way teachers think, understand and teach. This experience can shed light on curriculum choices for teachers’ education.

We present a comprehensive and updated Python-based open software to calculate continuous symmetry measures (CSMs) and their related continuous chirality measure (CCM) of molecules across chemistry. These descriptors are used to quantify distortion levels of molecular structures on a continuous scale and were proven insightful in numerous studies. The input information includes the coordinates of the molecular geometry and a desired cyclic symmetry point group (i.e., C_s, C_i, C_n, or S_n). The results include the coordinates of the nearest symmetric structure that belong to the desired symmetry point group, the permutation that defines the symmetry operation, the direction of the symmetry element in space, and a number, between zero and 100, representing the level of symmetry or chirality. Rather than treating symmetry as a binary property by which a structure is either symmetric or asymmetric, the CSM approach quantifies the level of gray between black and white and allows one to follow the course of change. The software can be downloaded from https://github.com/continuous-symmetry-measure/csm or used online at https://csm.ouproj.org.il.

Professional development courses help teachers integrate new content knowledge into the high-school curriculum. Designing practical online courses for this purpose is challenging, particularly in emerging fields such as nanotechnology. In this study, we evaluated such a course in three complementary dimensions: (1) knowledge, (2) the complexity of learners’ understanding, and (3) learners’ difficulties during the course. We evaluated the first aspect using a pre–post-knowledge test, the second using the Structure of the Observed Learning Outcome (SOLO) taxonomy applied to the course's assignments, and the third by analyzing online activity reports and semi-structured interviews. Three cohorts comprising 95 teachers participated in this course from 2016 to 2019. Our multi-dimensional analysis revealed that teachers’ knowledge of nanotechnology concepts improved. They were able to connect the advanced content they learned to the high-school chemistry curriculum at different levels of complexity. The evaluation process also enabled us to identify difficult sections of the course. These findings can contribute to designing the curriculum of future professional development online science courses in terms of the intended learning outcomes.