This is an app I downloaded one day when it was free. Geometric shapes is normally 99 cents and in my opinion it offers some nice advantages. It actually is focused on deciding the vocabulary word that is illustrated and selecting the letters to make the word. If the letter does not fit, it cannot be put into the space.
Today, I ended up having class in the computer lab because my room was flooded due to a burst water pipe last Friday and this morning the room reeked of mold and mildew so I could not use my room. In Algebra 2, I had one of my students get the white boards and markers from my room and the kids worked together to simplify the polynomials. They loved it and want to do it again. At the end of the class period, I decided there is nothing wrong with low tech as it is a type of technology. Sometimes I think that we (including myself) get too focused on the high tech things that we forget about technology we already had and used before the iPads. Collaboration low tech style.