Experiences

Optical isomerism (or stereoisomerism)

Laura Capella

Italy

Vocational School

Chemistry

Teaching in class

The optical isomerism is and important subject during the High School third/forth year, especially if you follow a Scientific School training. This matter is worth to be thoroughly investigated: it presents difficulties not easy to overcome.
Class has been divided into four-membered groups and everyone was given a very precise task. In this way all of them are involved in schoolwork better than in an ordinary exercise-job when only one person (teacher or student) does it on blackboard for the others. In this way everybody is compelled to pay attention and do the work, even enjoying it. In every group has been performed a rather good job especially when there is a diligent and clever pupil, but this was not necessary. To work well together is very important, so it is useful to let them mix together as they want, unless they are unproductive.
The task was doing several structures with plastic molecular models, after I had explained how to use them. The target was making some structures in which were present four different functional groups or atoms bind to a central carbon. Students’ major achievement would be realizing that for each four group pool there are two different geometrical isomers.
The really important thing is to assign a precise job to everybody: for example a member of the group has to pay attention to the Cahn-Ingold- Prelog Priority Rules, while another member has to assign the relative configuration (R or S) to the given compound structure. The most important job to assign is that somebody has to draw everyone attention to work and remember to the others to be quiet; another key task is to keep eye on clock, making sure there will be results in the duly time.
Teacher’s job is to facilitate students work while interacting with each group separately. At the end, some pictures were taken both from teacher and students. Students enjoyed quite much the activity.
Test examination was performed afterward with average good results.