Flashcards is the app everyone needs for studying. It allows you to create quizzes on your iPhone with a "stack" of flashcards that you use on your phone to study. You can let your friends play with you. When you want to, you can click on one of your quizzes and then press the Dual button to join up with one or more friends with their phones and let them see the question on their phones and you can see the answer. You are in control! You can press the next button, and everyone who is playing sees the change on their iPhone instantly. You can let everyone see the opposite of what they already see. If you want to, you can go solo and play alone with flashcards.