Geometry 2D-pad is the version of Geometry Drawer set up to maximize the ipad's ability. I tried playing with it a bit before I resorted to the help spot on the website because it was not as intuitively obvious to use. What is nice is that there is a blog you can access for instructions on constructing various geometric shapes using this app. This app actually has a users guide but you have to go to the blog site to find it and read it. If there are instructions contained within the app, I could not find them.
I think I need to play around with this app a bit more to actually figure out how to change dimensions of various shapes. I also plan to read more on the blog and check out the users manual to learn more. I think this has quite a bit of potential but until I figure it out, I cannot use it in class.