There are absolutely no advertisements or pop-ups in this app. I play it on i-phone and iPad. There are several games in Stack The States, but you cannot play them all immediately. You have to win enough states to advance to a new game, so success relies on some prior knowledge. This is not going to teach kids to identify the states if they are clueless to begin with, but it will reinforce what they know, and add to their sense of confidence or self-efficacy.
Playing the Stacking game is educational because you have to identify the state given 4 choices, but its also funny. I love watching the states facial expressions — the look in their eyes — as the stack wobbles or falls.
My only quibble is that the state flags are too small to read clearly. I wish they would expand quite a bit larger when I tap it.
There is another game where you have to place the states on a map as fast as possible, but with 3 strikes youre out. Good fun. Works better on iPad than iPhone, due to size.
The other games in the app are okay, too, but stacking and mapping are my favorites.