In general we try to use only free software. The reason for this is that we think that scientific software should be freely available. Another
reason is that we do not want our students to buy extensive software packages when they later decide at home that they want to extend their work they did in the course. Or to ger the packages from somewhere else ...
So as far as possible, we try tu use freeware, especially software that is licensed by the GPL.
We use the “Personal Learning edition” of VenSim, that is freely available here.
Models of self-organization and swarm intelligence
We use StarLogo, NetLogo and yabasic.
Currently we use Microsoft Excel, but we plan to switch to OpenOffice.
Currently we use Mathematica, which is available at our university. But also here we are seeking for a free alternative.