Teaching crystallography

Plato, the student of Socrates and the teacher of Aristotle, endorsed that the fundamental task of education is that of helping students to value reason and to be reasonable. Are there proper criteria for evaluating educational efforts and practices? The overall aim is the enhancement of understanding, production of knowledge and of knowledgeable students. Teaching materials may facilitate learning, may help students to evaluate, organize, integrate and retrieve information. Issue 3 of Volume 27 of Crystallography Reviews presents two articles, a topical and a tutorial one, on teaching crystallography from two eminent scientists and appreciated educators: Professors John Helliwell and Gervais Chapuis. While John Helliwell asks the question ‘How should we teach crystallography?’, Gervais Chapius offers an introduction to the diffraction of crystals. John Helliwell from the Department of Chemistry, University of Manchester, UK prepared ‘A review of teaching books contents pages’ screening around 30 crystallography textbooks. The survey of the sequence of chapters showed that in the majority of books the classical crystallography preceded the description of diffraction. However, his point is that a coursebook for those students who treat crystallography as a service should start with diffraction, the classical crystallography can follow explaining the results. Anyhow, a stand cannot be made for a unique way of explaining crystallography, since it depends on the science subject that a student comes from (physics, chemistry or biology), on the level of education (undergraduate, graduate or later), and on the desired depth of understanding of crystallography. Gervais Chapuis from École Polytechnique Fédérale de Lausanne, Switzerland, in his article ‘An elementary treatment on the diffraction of crystalline structures’ presents first the periodic nature of crystalline structures, followed by the crystallographic reference frames, and then by modelling the diffraction laws. Here, he introduces the Laue equation and its interpretation by the Ewald sphere as a start, then comes the interpretation of the Bragg equation. With this approach, Bragg’s law can be reformulated directly in terms of the reciprocal unit cell constants avoiding thus the necessity to introduce a priori the notion of lattice planes. The article is based on the lecture given during the summer school of the Italian Association of Crystallography on the Fundamentals of Crystallography in 2021. ‘A review on the structural and magnetic properties of differently doped bismuthferritemultiferroics’ completes this issue by S. R. Dhanya, Jyotirmayee Satapathy and Pavan Kumar from the Department of Physics, Amrita Vishwa Vidyapeetham, Amritapuri and Matrusri EngineeringCollege, Hyderabad, India. Bismuth ferrite is one among the recently identified multiferroic materials whose magnetic response increases with decreasing particle size and possesses antiferromagnetic ordering above room temperature. Doping with