GeoGebra for Android
GeoGebra and GeoGebraTube have been available to use in your web browser for a while now. Recently, I discovered that GeoGebra is also available as an Android app. The free GeoGebra Android app allows you to graph and create models much like you can do on your computer. The free GeoGebra Android app also includes access to GeoGebraTube, the gallery of things created by other GeoGebra users.
There are a couple of things to note about the GeoGebra Android app before you have all of your students install it. First, you need to have some familiarity with GeoGebra before trying the app. The app itself does not offer directions and is not intuitive for a first-time or infrequent user of GeoGebra. Second, some people are complaining of the app being laggy. On my Nexus 7 I didn’t experience any lag time, but on my Galaxy tablet I did.