Excel can be used to create neat little simulations for classroom traings. I remember a long time back, I had a tough time trying to understand how the strands of a DNA coil around each other. Well….I tired my hands at creating a rotating DNA strand using 3-D bubble charts…..stright ‘n simple for the most part……the trick lies in making the base and linking pairs change their overlaps after rotating every 180 degrees !!! You can download the simulation here.