Quizlet is an online learning tool based on flashcards that can be used for formative testing.
In Quizlet, you can enter study material in the form of flashcards, for example a word and its translation, or a term and its definition. After you have created your study set, you can study it in seven different ways: Flashcards, learn, write, spell, test, match and gravity. As a teacher, you can also play the studyset as a live game.
An example of a Quizlet (made by Greetje) has been embedded below. Click on 'study mode' (bottom right) to choose a different study mode than 'match'.