World Geography Quiz Game: Need to prep for a geography test, or just interested in learning more about the world? This app has more than 6,000 questions about maps, capitals, flags, currency, and much more.

GeoBee Challenge App: Find out if you have what it takes to compete in the National Geographic GeoBee! This app has more than 1,000 questions from past geography bees, including challenging bonus photo rounds.

Khan Academy: Khan Academy is a great resource to review SS content among many other subjects.

Stack the States 2: Part game, part educational tool, Stack the States helps kids learn geography and general knowledge about different states through a game. Each right answer leads to winning a state to add to your stack, and the ultimate goal is stacking your states to a certain height. The app keeps itself fun and fresh by offering three other games that kids can unlock as they complete different rounds. There’s also a version for countries.