I have downloaded a bunch of free games for my personal iPad, however they are more from practice not teaching. Yesterday I came across this website, National Library of Virtual Manipulatives. I only tried the algebra balance but it was great and I think you will want to use it.
Our district purchased textbooks that had online help tutorials to use. However, I use Khan academy as well. This takes a little research up front to find the right video, but they seem to have videos on everything. We also use Plato, which is something you have to purchase a license for.