Whether you've used Quizlet before or not, you will want to give Quizlet Live a try. It allows teachers to select a set of vocabulary words or math problems in Quizlet, and this use that as the basis of a review game that students play in teams. Students are given a game pin to enter the game.
Once they've entered the code, they will be randomly assigned to teams (teachers can reshuffle teams if you like). One of the advantages of Quizlet Live over some other review games is the focus is on accuracy, not speed. Teams earn points by making correct matches quickly, but their progress is reset to zero if they make a mistake. This should encourage teams to try to determine the absolute correct choice instead of "speed" guessing that often occurs in some review games.