I was lecturing along today, teaching the basics of the theory and how to interpret Tanabe-Sunago diagrams, and I got to my slides where I show them how to calculate ∆o from Co(en)3, and it just fell apart. I had done V(III) as a first example, and then I wanted the students to practice the calculations, but my slides were not up to the task. I thought to myself, in the moment, this would be a good opportunity to do an in-class activity, I should write it. So, in the spirit of making next year easier, I did. I have not used this in class, but I wish I had had it this morning. 

This exercises uses beads to help show how different crystal structures are formed.  The exercise includes 3D-printed boxes with starting structures incorporated in the bottom to increase the stability of structures that students build.  The exercise also includes a number of additional 3D-printed manipulatives to help students visualize the unit cells and other properties of different crystal structures.  These include unit cells with accurate atomic and hold dimensions and several different ways to visualize the layer structures in close-packed structures.