Web/iOS/Android: Whether you’re a student in school or a lifelong learner, using flashcards can help you retain the information you’re studying. StudyBlue is a crowd-sourced collection of these study aids.
We’ve mentioned StudyBlue before, but since then it’s changed (for the better). Now you can sign up without having to go to a college that’s connected to the app (although if your school is, you can add specific classes you’re taking) and in addition to making your own flash cards and testing yourself on them, you can access others’ flashcards on topics ranging from Algebra to Zoology.
There are decks for middle school, high school, college, and general topics such as business and technology.
The free version gives you suggested flashcard sets for the interests you add, and a paid version $7 a month (paid yearly) gives you full access to all 250+ million decks.