Teaching chemical bonding through project-based learning. Ii. Weighting “know how” and “know why” within the projects

Resumo

In previous issues we have reported some experiences with project-based learning. All of them were carried out by us when teaching fundamental concepts of Quantum Chemistry in a course placed in the second year of the Chemistry Degree. Introducing project-learning has worked really well avoiding the usual disconnection of many students from the mathematical deductions presented (using the expositive method), or proposed as homework. Nevertheless, we have noticed that our projects have not changed that our students tend to be more interested in acquiring solving skills (know how) they can use in front of an examination problem, than about reasoning which causes and/or first principles are behind what they are doing (know why). We identify this as a shortcoming in our teaching method, certainly shared by other methods, and even rooted within the philosophy basing some predominant trends in contemporary education. Students are clearly oriented by the way they are evaluated. In fact, for years we have noticed that many of them really learn how to pass the course. A clear example in our subject is: many students gain the ability to write (and solve) secular determinants implementing the Hückel treatment for delocalized systems. They solve the problem correctly, but they are unable to answer what is a secular determinant and why it appears there. We believe this kind of facts point to a new strategy. The projects given to students, and examinations too, should be designed weighting: i) technical abilities; and ii) rigorous reasoning from basic concepts. A comparative analysis of chemical bonding in two small cations has been the first project where we have included diverse theoretical questions preventing from routine and prompting students for searching which scientific reasons are behind the treatment they are employing. As in previous projects, the whole mathematical formalism behind chemical bond is applied. Thus, motivation for acquiring stronger abilities in solving numerical problems is guaranteed. When the results are presented in a seminar, the teacher plays a more significant role, highlighting the questions on fundaments and monitoring explanations.