This app simply provides students with rote practice of the algorithm for addition with regrouping. There are many free Java and Flash applications on the internet that accomplish the same thing, and even an old-fashioned worksheet would be as useful as this app if the goal is to simply have students drill and practice the algorithm. There are no conceptual supports here other than algorithmic steps that the app provides if the "help" or "hint" buttons are pressed. The app could be improved if an option were added to show how a model such as base ten blocks coincides with the numerical manipulations for a given sum. Such a change would provide a conceptual support for the algorithm, and also make this app "feel" more like an application that takes advantage of the affordances of technology. Again, as the app currently stands, it doesn't feel much different than the worksheets I used to plow my way through as an elementary student in the '80s.