Navigate 2.1.3 Commercial vs Open Virtual Classrooms

As I've mentioned before, I really love free and I really love open-sourced.  There are so many options for great educational resources online that I find it really difficult to pay for any of them; there are also a lot of people who can not pay for them and this should be of consideration as well.  I love the accessibility of knowing that I can reach my materials online rather than on a specific computer.  There are a few drawbacks that come to mind especially in regards to student use.  A lot of free programs have ads which can be dangerous for minors, annoying, and distracting.  There are also firewalls and privacy issues to be considered.