I teach VFX in a training center,and I wish to import Houdini into our training course. But first I must make sure whether I can use it without any legal problem. Which version should I use? Can I install the apprentice version onto our students' computer for free?
ps: We don't have any commercial projects now.We can assure you that we just use it for studying purpose.

get in touch with sidefx directly because they have special license for schools and you will get more support from them.

some more information:
http://www.sidefx.com/images/stories/learning/education/houdini_education.pdf [sidefx.com]
http://www.sidefx.com/index.php?option=com_content&task=view&id=1558&Itemid=326 [sidefx.com]