"The World HD" app is definitely relevant for my future classroom no matter what social studies I will end up teaching. It can be used for physical geography, human geography, history, communication, economics, and/or government. I really did enjoy the app. Although it doesn't so much fit into any "design" aspect I believe it's a great resource and facilitator of information. Students can learn about other places in a much more interactive way and at their own pace, as opposed to a traditional teacher just showing a world map on a globe or projector and requiring students to solely memorize locations. I think I would use this app as a database and resource center for students to gain information which they would then discuss and utilize in a paper or multimedia presentation.
I found out about this app by Google searching for the best apps to use in a secondary social studies classroom. The only thing I wish the app included was small formal assessments or self quizzes, so that students could test their knowledge.