I love our kindergarten unit on tangrams so I was eager to explore some of the apps that support that type of spatial learning. As a teacher who uses the Grandfather Tang book by Ann Tompert, I would love to find a program that begins with the shapes from that story. We use those templates of the fox, lion, goldfish, etc., in the classroom and the students love to solve the puzzles again and again. So far, I haven't found an app with those shapes or one that ties into that story (and is appropriate and fun for five and six year olds).
I began exploring with My First Tangrams HD. In this app, there are four levels of puzzles. The first level is very simple and each tan is outlined so there is little room for error. The second level shows a tiny picture of the finished puzzle and only one piece is outlined. In order to solve, the user needs to figure out which piece goes where. It goes on to two more levels, one of which is open for free tangram designs.
Ideally, an app would show an outline of the puzzle and leave it to the user to decide how to fill the puzzle with the seven tans. I think the My First Tangrams HD app is too guided. It leaves little room for flexible thinking. One of the great things about the traditional tangrams puzzles is that students need to struggle with the spacing of the tans to complete the picture rather than have a finished puzzle to copy. This only allows them to polish their duplication skills rather than the added spatial math component.
One other challenge with this app is that often a tan appeared as a much smaller version that needed to be placed off center to make the iPad accept completion. For kindergarteners (or anyone) this would become frustrating.
I am still on the search for a better tangram app - I am discovering that many of the apps for children don't have a "snap to" feature for the tans and need precise placement. The apps also don't offer something more than can be achieved by working with the actual Tangrams.